Reflection type projection screen, production process thereof, and production apparatus thereof

ABSTRACT

A reflection type projection screen is constituted as follows. Provided in order on a light absorbing layer 5, which is a dark plastic sheet or a solid print of a dark ink, are a fibrous sheet 4 of glass fibers, a white, opaque base material sheet 3made with a plastic sheet, and a light diffusing layer 2 of a translucent plastic into which a lustrous pigment or calcite powder is incorporated. An emboss 9 is formed on the outer surface of the light diffusing layer 1. It is preferable that a reflection layer 2 printed with an ink containing a lustrous pigment or calcite powder is provided below the light diffusing layer 1. Light absorbing stripes 11 are provided each at a position corresponding to a concave portion 9a of the emboss 9 on the surface of the base material sheet 3 adjoining the light diffusing layer 1. A production process and a production apparatus of a reflection type screen, which can efficiently produce reflection type screens with the emboss are also disclosed.

This application is a continuation of U.S. application Ser. No.07/972,451 filed Apr. 2, 1993 now abandoned.

TECHNICAL FIELD

The present invention relates to projection screens, specifically areflection type screen for projecting thereon a moving picture such as amotion picture, to a production process thereof, and to a productionapparatus thereof.

BACKGROUND ART

A screen used for projection of a slide or OHP, or, for projection of amovie or video is generally a lamination of a dark backing sheet and awhite polyvinyl chloride (PVC) film. Conventional screens have lowreflectivities and therefore dark projected images, so that theprojected images cannot be watched except in a dark room. In addition,the conventional screens have low diffusing powers, so that theprojected images cannot be watched except within a limited range ofangle to the screen surface.

There is a screen in which glass beads are bonded to the PVC film toenhance the reflectivity and the diffusing power. Such a screen,however, has unevenness on its surface and is easily contaminated.Therefore, the glass beads are readily scraped off when the contaminantsare wiped off from the surface thereof, which is a defect of such ascreen. If such a screen is used as a screen of wind-up type, the glassbeads will gradually drop off while the screen is wound and unwound manytimes, which is also a problem.

There is proposed ( in Japanese Laid-open Utility Model Publication No.Sho 64-40835) a screen comprising the dark backing sheet and the whitePVC film as described above, in which a metallized layer is provided asa reflection layer on the white PVC film, in which a translucent PVCfilm containing a pearl pigment is laminated thereon, and in which aspecific emboss is provided on the outer surface thereof.

A screen having a reflection layer of metal has a too high lightreflectivity and too many components of specular reflection (whereincidence angle =reflection angle), so that a halation is caused topresent a dull image projected. In addition, while a plastic sheet(mainly a polyester sheet) must be used with a strong adhesivity to themetallized layer in order to form the metallized layer as a reflectionlayer, there is a defect in that such a plastic sheet is likely to havecreases. In other words, there remain folds caused upon transfer orwind-up of the screen, and the high reflectivity makes the foldsoutstanding. These problems are serious if a screen should be of a bigpicture plane, for example, of 100 inches.

DISCLOSURE OF THE INVENTION

It is a first object of the present invention to provide a reflectiontype screen having a diffusing power and a reflectivity suitable for aprojection screen, which is free of creases and easy in handling.

It is a second object of the present invention to provide a reflectiontype projection screen which has high contrast even in a bright place tosecure a clear image while restraining disturbance of stray lights.

It is a third object of the present invention to provide a reflectiontype projection screen which, solving the problems as described,provides a beautiful image and can enhance a sound effect.

It is a fourth object of the present invention to provide a reflectiontype projection screen which can always assure a clear image, solvingthe above-mentioned problems.

It is a fifth object of the present invention to provide a process forproducing a reflection type projection screen having desired opticalproperties, which is advantageous in productivity in an industrialapplication.

It is a sixth object of the present invention to provide a process forreadily producing a reflection type projection screen having an embossand light absorbing stripes.

(1) A first feature of the present invention is a reflection typeprojection screen provided in order with a light absorbing layer of adark plastic sheet, a fibrous sheet of glass fibers, a base materialsheet of a white, opaque, flexible plastic, and a light diffusing layerof a translucent, flexible plastic into which a lustrous pigment orcalcite powder is incorporated, wherein a convexo-concave emboss isformed on the outer surface of the light diffusing layer (1).

(2) A second feature of the present invention is a reflection typeprojection screen provided in order with a base material whose bothfaces are dark, and a light diffusing layer made with a translucentplastic sheet into which a scaly lustrous pigment is incorporated.

(3) A third feature of the present invention is a reflection typeprojection screen provided in order with a light absorbing layer of adark plastic sheet, at least one of a fibrous sheet with flexibility anda base plate with stiffness, a base material sheet of a white, opaque,flexible plastic, a reflection layer printed with an ink containing alustrous pigment or calcite powder, and a light diffusing layer of atranslucent, flexible plastic containing a lustrous pigment or calcitepowder, wherein a convexo-concave emboss is provided on the outersurface of the light diffusing layer and wherein a number of smallopenings are provided at least at a position of a speaker located behindthe light absorbing layer, through which openings sounds may pass fromthe speaker.

(4) A fourth feature of the present invention is a reflection typeprojection screen provided in order with a light absorbing layer of adark plastic sheet, at least one of a fibrous sheet with flexibility anda base plate with stiffness, a base material sheet of a white, opaque,flexible plastic, a reflection layer printed with an ink containing alustrous pigment or calcite powder, and a light diffusing layer of atranslucent, flexible plastic containing a lustrous pigment or calcitepowder, wherein a convexo-concave emboss is provided on the outersurface of the light diffusing layer (301) and wherein theconvexo-concave pattern of the emboss has either no periodicity or aperiodicity with a periodic direction of the convexo-concave patterninclined at an angle of 15-75 degrees to a direction of arrangement ofprojection pixels.

(5) A fifth feature of the present invention is a process for producinga reflection type screen, comprising:

rotating a rotary intaglio with a surface having a fine convexo-concavepattern in lens form, filling at least recess portions of the rotaryintaglio with an ionizing radiation curing resin liquid, and pressingagainst the rotary intaglio a support sheet of a transparent, flexibleplastic traveling in the rotation direction of the rotary intaglio insynchronism therewith;

rotating the rotary intaglio so as to keep the support sheet in contactwith the rotary intaglio, and irradiating said ionizing radiation curingresin liquid with an ionizing radiation to cure the resin liquid andsimultaneously to effect adhesion between the cured resin layer and thesupport sheet,

separating the support sheet together with the cured resin layer fromthe rotary intaglio to thereby make a lens sheet in which a fineconvexo-concave cured resin layer in lens form is formed on one face ofthe support sheet; and

laminating a backing base material with light diffusing and reflectingproperties on the non-lens face of the lens sheet.

(6) A sixth feature of the present invention is a process for producinga reflection type screen, comprising:

printing light absorbing stripes with a light absorbing ink on one faceof a support sheet of a transparent, flexible plastic;

rotating a rotary intaglio with a surface having a fine convexo-concavepattern in lens form, filling at least recess portions of the rotaryintaglio with an ionizing radiation curing resin liquid, letting thesupport sheet travel in the rotation direction of the rotary intaglio insynchronism therewith, and pressing the other face of the support sheetagainst said rotary intaglio;

rotating the rotary intaglio so as to keep the support sheet in contactwith the rotary intaglio, and irradiating the ionizing radiation curingresin with an ionizing radiation to cure said curing resin andsimultaneously to effect adhesion between the cured resin layer and thesupport sheet;

separating the support sheet together with the cured resin layer fromthe rotary intaglio, printing light absorbing stripes on one face of thesupport sheet, and producing a lens sheet provided with the cured resinlayer having a convexo-concave lens surface in which a recess portion islocated at a position corresponding to each light absorbing stripe; and

laminating a backing base material with light diffusing and reflectingproperties on the face of the lens sheet adjoining the light absorbingstripes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view showing a first embodiment of areflection type projection screen according to the present invention;

FIG. 2 is a sectional side view showing a modification of the reflectiontype projection screen as shown in FIG. 1;

FIG. 3 is a sectional side view showing another modification of thereflection type projection screen as shown in FIG. 1;

FIG. 4 is a sectional side view showing a still another modification ofthe reflection type projection screen as shown in FIG. 1;

FIG. 5 is a plan view of the reflection type projection screen as shownin FIG. 1;

FIG. 6 is a sectional side view showing a second embodiment of thereflection type projection screen according to the present invention;

FIG. 7 is a diagram to illustrate a locus of projection light in thereflection type projection screen as shown in FIG. 6;

FIG. 8 is a diagram to illustrate a locus of stray light in thereflection type projection screen as shown in FIG. 6;

FIG. 9 is a sectional side view showing a third embodiment of thereflection type projection screen according to the present invention;

FIG. 10 is a sectional side view showing a modification of thereflection type projection screen as shown in FIG. 9;

FIG. 11 is a plan view of the reflection type projection screen as shownin FIG. 9;

FIG. 12 is a sectional side view showing a fourth embodiment of thereflection type projection screen according to the present invention;

FIG. 13 is a sectional side view showing a modification of thereflection type projection screen as shown in FIG. 12;

FIG. 14 is a plan view of the reflection type projection screen as shownin FIG. 12;

FIG. 15 is a plan view to show a picture plane to be projected onto aprojection screen;

FIG. 16 is a diagram to show a direction of period of emboss on aprojection screen and a direction of arrangement of projection pixels ofthe picture plane;

FIGS. 17, 18, and 19 are a plan view, a partial perspective view, and asurface contour reperesentation to show states of an emboss without aperiodicity on a projection screen;

FIG. 20 is a side view showing a first embodiment of a productionprocess of a reflection type projection screen according to the presentinvention;

FIG. 21 is a side view showing a modification of the production processof the reflection type projection screen;

FIG. 22 is a sectional view showing a lamination step in a productionprocess of the reflection type projection screen;

FIG. 23 is a sectional view showing another lamination step in aproduction process of the reflection type projection screen;

FIGS. 24(A) and 24(B) are side views showing another modification of theproduction process of the reflection type projection screen;

FIGS. 25(A) through 25(E) are sectional views showing examples of insidestructures of the intaglio roll shown in FIG. 24;

FIGS. 26 through 30(B) are a sectional view, a fragmentary perspectiveview, a sectional view, a schematic side view, and plan views indicatinga second embodiment of the production process of the reflection typeprojection screen according to the present invention; and

FIGS. 31, 32, and 33 are a perspective view and plan views showing afirst embodiment of the reflection type projection screen according tothe present invention, in which an emboss pattern of fly eye lens groupand a light absorbing portion are shown.

BEST MODES FOR CARRYING OUT THE INVENTION §1 First Embodiment ofReflection Type Projection Screen 1.1 Fundamental Constitution

A first embodiment of a reflection type projection screen according tothe present invention will now be described with reference to FIGS. 1 to5.

The first embodiment of the reflection type projection screen accordingto the present invention, as seen in FIG. 1 to show a cross sectionthereof, is provided in order on a light absorbing layer 5 of a darkplastic sheet with a fibrous sheet 4 of glass fibers, a base materialsheet 3 of a white, opaque, flexible plastic, and a light diffusinglayer 1 of a translucent, flexible plastic into which a lustrous pigmentor calcite powders are incorporated, in which a corrugated orconvexo-concave emboss 9 is provided on the outer surface of the lightdiffusing layer 1.

A modification embodiment of the above is a reflection type projectionscreen as shown in FIG. 2. In detail, it is provided in order on a lightabsorbing layer 5 of a dark plastic sheet with a fibrous sheet 4 ofglass fibers, a base material sheet 3 of a white, opaque, flexibleplastic, a reflection layer 2 printed with an ink containing a lustrouspigment or calcite powders, and a light diffusing layer 1 of atranslucent, flexible plastic into which a lustrous pigment or calcitepowders are incorporated, in which an emboss 9 is provided on a surfaceof the light diffusing layer 1.

The plastics used for the base material sheet 3 and for the lightdiffusing layer 1 are any of flexible plastics, for example,specifically a polyvinyl chloride, suitably a polypropylene and apolyethylene. Particularly preferable is a soft material in which aplasticizer is added by 50-60 parts by weight to 100 parts by weight ofpolyvinyl chloride. The thickness of the base material sheet 3 ispreferably between 0.05 and 1 mm.

Usable as the base material sheet 3 is a sheet formed by kneading awhite pigment and a lustrous pigment in a plastic. It is, however,difficult to obtain a large quantity of coarse grains of lustrouspigment uniformly dispersed in a plastic. Also, it is not advantageousto use a large quantity of expensive lustrous pigment. Further, such asheet has a low flexibility. Therefore, it is advantageous to print theink containing the lustrous pigment on the sheet formed by kneading onlya white pigment therein.

Examples are listed as follows for the lustrous pigment which may beincorporated into the light diffusing layer 1 and the reflection layer2: (a) materials called pearl pigments, specifically, ground insideportion of seashells, ground pearl, mica, finely divided particles ofmica with TiO₂ or ion oxide baked thereon; (b) metal powders,specifically, copper, aluminum, brass, bronze, gold, silver, preferably,of finely divided particles of 1-120 μm; (c) splinters of depositedplastic film, for example a material obtained by depositing a metal aslisted above, normally aluminum, onto a polyethylene terephthalate filmand grinding it. The lustrous pigment is preferably scaly in shape.Arranging surfaces of scaly bodies of the lustrous pigment in parallelwith a plane of the base material sheet enhances irregular reflection ofhigh luminance.

The powder of calcite incorporated into the light diffusing layer 1 andthe reflection layer 2 preferably has an average grain size of 2-20 μm,and preferably has a size distribution as narrow as possible. Forexample in case of an average grain size of 5 μm, a preferable sizedistribution is such that more than 80% by weight drop in a rangebetween 3 and 7 μm.

The amount of the lustrous pigment or the calcite powder added into theplastic for the light diffusing layer 1 is between 0.5 and 10% byweight, specifically preferably about 2% by weight.

The ink printed on the base material sheet 3 to form the reflectionlayer 2 is an ink in which a lustrous pigment or calcite powder isdispersed in a normal ink vehicle. Examples of the vehicle are polyvinylchlorides, polyvinyl chloride-polyvinyl acetate copolymers, acrylicresins, polyurethanes, and polyesters. Although it is preferable thatthe proportion of the lustrous pigment in the ink be as high aspossible, an excessively low ratio of the vehicle makes the formation ofthe print layer on the base material sheet difficult. Thus, a preferablecomposition of the ink is 5-50 parts by weight of the vehicle to 100parts by weight of the pigment. The thickness to be coated by printingis ordinarily about 1-10 μm.

Such an ink into which coarse grains of lustrous pigment are dispersedtends to cause unevenness upon printing. Obtaining a desired thicknessby a single printing should be avoided. A lap printing is preferable toobtain a desired thicknesses of layers by repeating a printing offractional thickness several times, obtaining a high reflection power ofthe light diffusing layer 1.

In the case of use of the calcite powder, a preferable composition ofthe ink is defined by the same reasoning as above such that 10-100 partsby weight, specifically 10-50 parts by weight, of the vehicle are addedto 100 parts by weight of the calcite powder.

The printing to form the reflection layer 2 may be carried out by anyone of known techniques such as printing methods of the gravure process,the silk screen process, and the like, and coating methods such as thespray coating, the roll coating, and the like. A sufficient thickness ofthe print layer is 1 μm or more in a dry state.

An appropriate thickness of the light diffusing layer 1 is between 0.04and 0.8 mm in the case of no provision of the reflection layer 2, basedon a consideration to reduce an attenuation amount of reflected light tokeep projected images bright enough. In the case of provision of thereflection layer 2, the attenuation of reflected light amount is low,and, therefore, an appropriate thickness is between 0.05 and 1 mm inview of broadening a half-value angle by increasing the thickness of thelight diffusing layer.

The fibrous sheet 4 is for enhancing the dimensional stability of thescreen. Specifically, when the screen is used as a wind-up screen, thebase screen is required to prevent the screen pulled down from sagging.Also, when the screen wound up for storage is again unwound in use forprojection, a remaining curling causes a projected image to be warped.Thus, the fibrous sheet 4 is required to have a sufficient elasticrecovery and a sufficient stiffness. Materials to meet theserequirements are a woven fabric or an unwoven fabric of glass fibers, aplastic sheet such as a polyester and a cellulose triacetate which isgiven a flexibility with many small pores.

The plastic sheet for the light absorbing layer 5 is made byincorporating a dark, for example black, dark brown, or dark blue,pigment into a plastic material as used for the base material sheet andby forming it. The screen is preferably balanced in a direction ofthickness, if a thickness of the sheet is set substantially equal to thetotal thickness of the base material sheet 3 and the light diffusinglayer 1 or to the total thickness of the base material sheet 3, thereflection layer 2, and the light diffusing layer 1.

The above-described screen can be produced by heating and pressing forunification the plastic sheet for the light absorbing layer 5, the lightdiffusing layer 1 or a lamination of the reflection layer 2 and thelight diffusing layer 1, and the fibrous sheet 4 of glass fiberssandwiched between the foregoing elements, and by simultaneouslyimparting an emboss on the surface of the diffusing layer. Theunification may be effected by either of the fusion bonding method andthe dry lamination method.

The lamination of the base material sheet 3 and the light diffusinglayer 1 can be made by laminating the plastic sheet for the lightdiffusing layer 1 on the base material sheet 3 (or on the reflectionlayer 2 if it is provided), or, by coating a sol of the plastic for thelight diffusing layer thereon.

A pattern of the convexo-concave emboss 9 may be a pattern in whichwaves intersect each other at 90 degrees, which is frequently used inconventional reflection type screens. The pattern may be alsoarbitrarily chosen from those of a fly eye lens group, a graining look,a hairline look, etc. In the case where the audience spreads right andleft as well as in front of the screen, the light should be diffusedhorizontally at a large half-value angle. For this purpose, an emboss ispreferable with a semitubular lenticular lens group with axes thereofbeing vertical.

Further, as shown in FIG. 1, light absorbing stripes 11 are provided onthe surface of the base material sheet 3 on the side of the lightdiffusing layer 1 at locations other than areas on which the projectionlight is converged and projected (normally at positions corresponding toconcave portions 9a of the emboss 9, because the projection light entersthe projection screen in a direction close to the normal line thereof).The light absorbing stripes 11 are formed by printing with a black ink.For example, if the light absorbing stripes 11 are located at thepositions corresponding to the concave portions 9a of the emboss 9comprised of the semitubular lenticular lens group, they may absorbunnecessary stray lights (light from electric lamp, outside sunlight,etc.) incident from the emboss 9 side. That is, a general projectionlight is incident into the screen in a direction substantially normal tothe screen, and converges at the positions corresponding to the concaveportions 9b of the emboss 9 on the base material sheet 3. A stray lightincident at an angle greatly inclined to the screen converges at aconcave portion 9a of the emboss 9 and is absorbed by a light absorbingstripe 11. The light absorbing stripes are not absolutely necessary.

If the pattern of the convexo-concave emboss 9 is a fly eye lens groupinstead of the lenticular lens group, the light absorbing stripes 11cannot always be striped but may be of a network pattern for example inthe case of the fly eye lens group, in which the light absorbing portionis defined only in regions other than those immediately below convexportions of respective lenses.

With reference to FIGS. 31-33, the light absorbing portion in the casewhere the pattern of the convexo-concave emboss is of the fly-eye lensgroup will now be described. FIG. 31 is a perspective view of thereflection type projection screen, FIG. 32 is a plan view showing thelight diffusing layer, and FIG. 3 a plan view showing the reflectionlayer portion.

In FIGS. 31-33, the pattern is of the convexo-concave emboss 9. FIG. 32shows the fly-eye lens group pattern. As shown in FIG. 32, theconvexo-concave emboss 9 has concave portions 9a and convex portions 9b.The convex portions 9b are convex parts of the fly-eye lens group. Thelight absorbing portion 11 of network pattern is provided at portionsother than those immediately below the convex portions 9b (or atportions corresponding to the concave portions 9a) on the reflectionlayer 2 (see FIG. 33). A projection light incident in the directionsubstantially normal to the reflection type projection screen convergesat portions corresponding to convex portions 9b on the reflection layer2, and other stray lights converge at portions corresponding to theconcave portions 9a on the reflection layer 2 to be absorbed by thelight absorbing portion 11.

Also, as shown in FIG. 2, the light absorbing stripes 11 are provided atpositions corresponding to the concave portions 9a of the emboss 9 onthe surface of the reflection layer 2 on the light diffusing layer 1side.

FIG. 3 shows a second modification embodiment of the reflection typeprojection screen according to the present invention. As shown in FIG.3, the reflection type projection screen is provided in order, on anon-printed surface of a base material sheet 3 of a white, opaque,flexible plastic having a solid print layer or light absorbing layer 6of a dark ink, with a fibrous sheet 4 of glass fibers and a lightdiffusing layer 1 of a translucent, flexible plastic into which alustrous pigment or calcite powder is incorporated, in which an emboss 9is provided on the outer surface of the light diffusing layer 1.Further, as shown in FIG. 3, light absorbing stripes 11 are provided atpositions corresponding to concave portions 9a of the emboss 9 on thesurface of the fibrous sheet 4 adjoining the light diffusing layer 1.

The reflection type projection screen as shown in FIG. 3 may also bemodified as shown in FIG. 4 as a modification embodiment similarly asdescribed above. In detail, the modified screen is provided in order, ona non-printed surface of a base material sheet 3 of a white, opaque,flexible plastic having a solid print layer or light absorbing layer 6of a dark ink, with a fibrous sheet 4 of glass fibers, a reflectionlayer 2 printed with an ink containing a lustrous pigment or calcitepowder, and a light diffusing layer 1 of a translucent, flexible plasticinto which a lustrous pigment or calcite powder is incorporated, inwhich an emboss 9 is provided on the outer surface of the lightdiffusing layer 1. Also, light absorbing stripes 11 are provided atpositions corresponding to concave portions 9a of the emboss 9 on thesurface of the reflection layer 2 adjoining the light diffusing layer 1.

The same materials as described above may be used for the base materialsheet 3, for the fibrous sheet 4, for the light diffusing layer 1 of thetranslucent plastic sheet, and for the pigments. The light absorbinglayer 6 may be formed using a normal printing in a known technique suchas the gravure process and the screen process. The production of thereflection type projection screen may be conducted similarly as above bylaminating and bonding with heat and pressure the base material sheet 3,the light diffusing layer 1 of the translucent plastic sheet, and thefibrous sheet 4 sandwiched between the foregoing elements, and bysimultaneously imparting the emboss 9 thereon.

An outer frame 10 is printed with a dark ink as shown in FIG. 5 on thesurface of the reflection type projection screen as shown in either ofFIGS. 1-4 by an appropriate method such as the silk screen printing. Theouter frame 10 is effective for trimming of the image at the edge,making a picture plane clearer. Therefore, the outer frame 10 is arecommended feature.

A further feature to improve capabilities to diffuse and reflect lightto increase the half-value angle is such that formation of fibers andunevenness of weave pattern constituting the fibrous sheet 4 are raisedon a surface of the base material sheet. The fine unevenness on the basematerial sheet surface contributes to enhancing the properties ofdiffusion and reflection of light.

1.2 Operation

According to the projection screen of the present invention, the lightdiffusing layer 1 of the translucent plastic containing the lustrouspigment or the like is superimposed on the white, opaque base materialsheet, whereby a suitable diffusing power and a high reflectivity can beattained for the reflection type screen.

A part of light projected from a projector to the reflection type screenis reflected by the light diffusing layer 1. Another part thereofadvances into the light diffusing layer, is slightly diffused therein,is reflected at the surface of the base material sheet 3, again advancesinto the light diffusing layer 1, and then goes out of the reflectiontype screen. The emboss 9 on the reflection type screen surface refractsthe light entering and leaving the surface therethrough. As described,the reflection light spreads in a broad range of angle withoutlimitation to a specific direction, whereby the reflection isaccomplished with a suitable diffusion. In the arrangement withprovision of the reflection layer 2, a high rate of reflection can beaccomplished to obtain a high luminance on the screen surface.

1.3 Specific Examples Example 1

A black PVC sheet (DOP: 60 phr) of a thickness of 0.2 mm was employed asa light absorbing layer 5. Superimposed in order on the PVC sheet were afibrous sheet 4 of glass woven fabric, a white PVC calender sheet (basematerial sheet 3) (DOP: 60 phr) of thickness of 0.13 mm, a translucentPVC sheet (light diffusing layer 1) (DOP: 60 phr) of thickness of 0.12mm formed by kneading about 2% by weight of pearl pigment (titaniumcoated mica) and extruding it, and an emboss plate of graining look.These materials were integrally bonded and embossed by heat pressdoubling. The half-value angle was measured for the resultant reflectiontype projection screen of the present invention. The measured value ofthe half-value angle was 45 degrees. The half-value angle is aninclination in a horizontal direction at which brightness becomes halfof that in front of the screen, with respect to the normal line. Thisspecific Example 1 corresponds to the reflection type projection screenshown in FIG. 1.

Example 2

The base material sheet 3 was a white PVC calender sheet (DOP: 60 phr)of thickness of 0.13 mm. A sheen ink with a composition as describedbelow was printed on the base material sheet to a dry thickness of 3 μmby the gravure process, obtaining a reflection sheet composed of thebase material sheet 3 and the reflection layer 2.

    ______________________________________                                        Vehicle (PVC)        100 parts by weight;                                     Pigment (titanium coating mica)                                                                     20 parts by weight.                                     ______________________________________                                    

A black PVC sheet (DOP: 60 phr) of a thickness of 0.28 mm was used forthe light absorbing layer 5. Superimposed in order on the PVC sheet werea fibrous sheet 4 of glass fiber woven fabric, the above reflectionsheet 3 and 2, a translucent PVC sheet (light diffusing layer 1) (DOP:60 phr) of a thickness of 0.15 mm formed by kneading about 2% by weightof pearl pigment (titanium coating mica) and extruding it, and an embossplate of graining look. These materials were integrally bonded andembossed by heat press doubling. The half-value angle of the resultantreflection type projection screen of the present invention was measured.The measured value of the half-value angle was 45 degrees. This specificexample 2 corresponds to the reflection type projection screen shown inFIG. 2.

Comparative Example

A reflection type projection screen was produced as in Example 1 exceptthat the translucent PVC sheet (light diffusing layer 1) was omitted.The half-value angle of the resultant screen was 25 degrees.

Example 3

A white PVC calender sheet of a thickness of 0.20 mm as the basematerial sheet 3, a fibrous sheet 4 of glass fiber woven fabric, and atranslucent PVC sheet (light diffusing layer 1) of a thickness of 0.20mm similar to that in Example 1 were prepared. The light absorbing layer6 was formed by solid printing with a black ink with a pigment of carbonblack on the base material sheet 3. Superimposed on a non-printedsurface of the base material sheet 3 were the fibrous sheet 4 and thetranslucent sheet (light diffusing layer 1) provided with a print layer2 of a thickness of 5 μm with a sheen ink of Example 2 in such a statethat the printed surface was down. These materials were integrallybonded and embossed in the same manner as in Example 1.

An outer frame 10 of a black line of a width of 3 cm was printed by thesilk screen printing with a black ink on the screen surface thusobtained, producing a reflection type projection screen of the presentinvention squared with a diagonal line of 100 inches in length. Thisspecific Example 3 corresponds to the reflection type projection screenshown in FIG. 4.

1.4 Effect

The projection screen of the present invention makes possible theprojection of a high quality image with a high luminance on a largepicture plane without a difference in brightness at any view angle tothe screen, and therefore can be used in combination with variousprojecting means such as a liquid crystal projector. §2 SecondEmbodiment of Reflection Type Projection Screen

2.1 Fundamental Constitution

A second embodiment of the reflection type projection screen accordingto the present invention will be described in the following withreference to FIGS. 6-8.

The reflection type projection screen in this second embodiment of thepresent invention has a constitution as shown in FIG. 6 wherein a lightdiffusing layer 101 of a translucent plastic sheet in which aplatelet-shaped lustrous pigment 102 is incorporated is provided on abase material 103, the two faces of which are dark, for example, black,dark brown, or dark blue.

If the reflection type projection screen is used as a fixed type screen,the base material used should be a material with stiffness, for example,a metal plate such as a steel sheet or an aluminum plate, a wood plate,or a plastic plate.

On the other hand, if the screen used as a wind-up type screen, the basematerial 103 should be a flexible sheet in which a fibrous sheet 105 ofglass fibers and a middle sheet 106 of a dark plastic sheet arelaminated on a backing sheet 104 of a dark plastic sheet as well, asshown in FIG. 6.

The backing sheet 104 of the dark plastic sheet may be a plastic sheetinto which a dark pigment, for example, an aniline black, a carbonblack, or a red oxide, is incorporated, or a sheet on which a solidprinting has been conducted with a dark ink. The plastics used for thebacking sheet 104 and for the middle sheet 106 may be any of flexibleplastics, for example, a polyvinyl chloride as a representativematerial, in addition, a polyolefin such as a polypropylene or apolyethylene, a polyester such as a polyethylene terephthalate, apolystyrene, a polycarbonate, and an acrylic resin. Particularlypreferable is a soft or semirigid material in which a plasticizer ismixed in a quantity of 10-70 parts by weight, preferably 50-60 parts byweight to 100 parts by weight of polyvinyl chloride. Both thicknesses ofthe backing sheet 104 and of the middle sheet 106 are preferably withina range of 50-1000 μm.

The fibrous sheet 105 is for increasing the dimensional stability of thescreen. Especially, when the screen is used as a wind-up screen, thefibrous sheet 105 is required to prevent the screen pulled down fromsagging. When the screen is unwound in use for projection after storagein a wound condition, a remaining curling would cause an image projectedto be warped. Therefore, the fibrous sheet 105 is required to have asufficient elastic recovery and a sufficient stiffness. A material tosatisfy these requirements is a woven fabric or an unwoven fabric ofglass fibers.

The plastic used for the light diffusing layer 101 is the same as thatused for the backing sheet 104 and the middle sheet 106 as describedabove.

Examples of the lustrous pigment 102 are: (a) materials called pearlpigments, specifically, ground inside portion of seashells, groundpearl, mica, finely divided particles of mica with TiO₂ or ion oxidebaked thereon; (b) metal powders, specifically, copper, aluminum, brass,bronze, gold, silver, preferably, as finely divided particles of 1-120μm; (c) splinters of deposited plastic film, for example a materialobtained by depositing a metal as listed above, ordinarily aluminum,onto a polyethylene terephthalate film and grinding it. The lustrouspigment 102 chosen from the above should have a scaly shape. The amountof addition of the scaly lustrous pigment into the plastic is preferably0.5-10% by weight, particularly 2% by weight.

The thickness of the light diffusing layer 101 is preferably between 40and 800 μm, taking into consideration that an image projected should bekept bright while reducing an attenuation amount of reflected light.

A convexo-concave emboss 109 may be formed on a surface of the lightdiffusing layer 101. A pattern of the emboss 109 may be one with wavesintersecting at 90 degrees, which is often used in conventionalreflection type screens. If a light is expected to be diffused at alarge half-value angle in a horizontal direction, a preferable emboss109 is one to give a semitubular lenticular lens group with axes thatare vertical. From the view point that moire fringes should be preventedfrom appearing on the screen, a convexo-concave pattern without aperiodicity is preferable, such as a satin, a graining, or a hairline.Such a pattern is preferable especifically for an image of a liquidcrystal display device having rectangular pixels. In the case where aconvexo-concave pattern with a periodicity, such as a pattern with wavesintersecting at 90 degrees, which is often used in conventionalreflection type projection screens, or a pattern with lattice,rectangular, or hexagonal cell recesses continuing, is employed, thedirection of period of the convexo-concave pattern should be set at aninclination of 15-75 degrees to the periodic direction of the projectionpixels. Light absorbing stripes 111 are provided at positionscorresponding to concave portions 109a of the emboss 109 on the surfaceof the base material 103 adjoining the light diffusing layer 1. That is,the concave portions 109a are located at regions other than those onwhich the projection light is converged, because the projection lightenters the projection screen in a direction close to the normal linethereto.

The above screen can be produced by superimposing the plastic sheets forthe base material 103 and for the light diffusing layer 101, andintegrally bonding them together with heat and pressure. If a laminationas above described is used as the base material 103, the screen may bemade by first making the base material 103 and then laminating the lightdiffusing layer 101 on the base material as described above, or, bysandwiching the fibrous sheet of glass fibers between the backing sheet104 and the lamination of the middle sheet 106 and the light diffusinglayer 101, and bonding them together with heat and pressure. Thelamination can be carried out by the fusion bonding process or by thedry laminating process. The lamination of the light diffusing layer 101on the base material 101 or on the middle sheet 106 is also possible bycoating an ink, a coat, or a sol of the plastic for the light diffusinglayer 101, on the base material 103 or on the middle sheet 106.

If the emboss 109 is to be provided on the surface of the lightdiffusing layer 101, the emboss may be made simultaneously with thelamination, or, the emboss 109 may be made on the plastic sheet for thelight diffusing layer 101 to be unified with the base material. In thelatter, the concave and convex pattern should be formed of a cured resinin order to prevent the concave and convex pattern on the surface of thelight diffusing layer 101 from being crushed by heat and pressure uponlamination. A preferable method for forming the concave and convexpattern on the sheet surface with the cured resin is the drum printingmethod using an ionizing radiation curing resin (Japanese Laid-openPatent Publication No. Hei 2-131175).

An outer frame 10 (see FIG. 5) using a dark ink may be printed by asuitable method such as the silk screen printing on a surface of thereflection type projection screen of the present invention. The outerframe 10 makes a picture plane clearer with proper trimming at the edgesof the image. Therefore, the outer frame is a recommended feature.

For imparting a feeling of reality at the time of use of the projectionscreen, speakers may be positioned behind the screen and a number ofsmall openings may be made through the screen at the positions of thespeakers. A suitable size of the small openings in the screen is 0.5-2.0mm in diameter. If opening proportion of the small openings is too high,the openings could be disturbing for the audience, who could see throughthe screen. If the opening proportion is too low, sounds will not passeasily through the openings. Therefore, the opening proportion of thesmall openings is preferably between 15 and 65%, specifically between 30and 50%. The "opening proportion" is the proportion of the total area ofthe small openings to the portion of the screen through which soundspass. The shape of the small openings is preferably a circle or anellipse without a sharp angle, which is resistant to tearing when thescreen is pulled. The small openings may be provided over the entiresurface of the screen if desired. If the positions of the speakerslocated behind the screen are fixed as in a fixed screen, the smallopenings may be provided only at portions facing the speakers.Perforation of the screen can be carried out by punching with cuttingdie, drilling, or melting with CO₂ laser.

2.2 Operation

A projection light enters the projection screen in a direction close tothe normal direction thereto, while a stray light from the outside ofwindow or from an electric lamp inside a room enters the projectionscreen in a direction inclined with respect to the normal line. In theproduction of the light diffusing layer 101, the scaly lustrous pigment102 exists therein in such a state that layer planes thereof aresubstantially in parallel with the surface of the projection screen.

Let the quantity of a projection light incident into the projectionscreen be L_(p), the quantity of stray light be L_(s), the quantity ofthe projection light reflected and leaving be R_(p), and the quantity ofthe stray light reflected and leaving be R_(s).

Letting the rate of area occupied by the lustrous pigment 102 in theoverall area when seen in a direction of the projection light on theprojection screen (represented by the normal line) be K, the lightamount L_(p) of the incident projection light may be separated into aportion K×L_(p) where the projection light is incident onto the surfaceof pigment and the other portion (1-K) ×L_(p) where the projection lightreaches the surface of the base material through spaces between pigmentparticles, as shown in FIG. 7.

Similarly, letting the rate of area occupied by the lustrous pigment inthe overall area of the projection screen when seen in a direction ofthe stray light (represented by an inclination θ, though there are manystray lights incident in various directions inclined to the normal line)be K', the light amount L_(s) of the incident stray light may beseparated into a portion K'×L_(s) where the stray light is incident ontothe surface of pigment and the other portion (1-K')×L_(x) where thestray light reaches the surface of the base material, as shown in FIG.3.

In a conventional projection screen using a white base material,assuming that the reflectivity of the surfaces of the lustrous pigmentand of the white base material is 100%, the light amount R_(p) of thereflected projection light and the light amount R_(s) of the reflectedstray light may be respectively calculated as follows:

    R.sub.p =1×K×L.sub.p +1×(1-K)×L.sub.p =L.sub.p (1);

    Rs=1×K'×L.sub.s +1×(1-K')×L.sub.s =L.sub.s (2).

The SN ratio, i.e., a ratio of the light amount of the projection lightto the light amount of the stray light, is as follows:

    R.sub.p /R.sub.s =L.sub.p /L.sub.s                         (3).

There is no difference in the SN ratio between the reflection light andthe incident light, and therefore no improvement is achieved.

Since the projection screen of the present invention uses the black basematerial 103, the reflectivity of the surface thereof is approximatelyequal to 0%. Thus,

    R.sub.p =1×K×L.sub.p +0×(1-K)×L.sub.p =K×L.sub.p                                          (4);

    R.sub.s =1×K'×L.sub.s +0×(1-K')×L.sub.s =K'×L.sub.s                                         (5).

The SN ratio may be expressed as follows:

    R.sub.p /R.sub.s =K×L.sub.p /K'×L.sub.s        (6).

As seen from comparison between FIGS. 7 and 8,

    K'=K×cos θ                                     (7).

Since cos θ<1 under a condition of θ>0,

    K'<K, that is, K/K'>1                                      (8).

Arranging the equation (6),

    (R.sub.p /R.sub.s)/(L.sub.p /L.sub.s)=K/K'.

Then,

    R.sub.p /R.sub.s >L.sub.p /L.sub.s.

Thus, the SN ratio of the reflection light is improved as compared tothat of the incident light. Therefore, a projection image can beprojected with a high contrast.

As explained, the projection screen of the present invention is notreadily affected by stray lights as compared to the conventionalprojection screens and therefore can provide a clear image even whenused in a bright place.

2.3 Specific Example

A black polyvinyl chloride sheet (DOP: 60 phr) of a thickness of 200 μmin which a carbon black pigment was incorporated was prepared as abacking sheet 104 to be used as a base material 103 after lamination.Further, a fibrous sheet 105 of a glass fiber woven fabric and a blackPVC calender sheet (DOP: 60 phr) of a thickness of 130 μm in which acarbon black pigment was incorporated to be used as a middle sheet 106were prepared.

The fibrous sheet 105 and the middle sheet 106 were superimposed inorder on the above backing sheet 104. Further superimposed thereon inorder were a translucent polyvinyl chloride sheet (DOP: 60 phr) of athickness of 120 μm as a light diffusing layer 101, which was formed bykneading about 2 % by weight of a pearl pigment (scaly titanium coatedmica with an average grain size of 17 μm) in PVC and extruding it, and amatte emboss plate of graining look. These materials were bondedintegrally in lamination and embossed by heat pressing. Separated fromthe embossing plate after cooling, a reflection type projection screenof the present invention was obtained.

2.4 Effect

The projection screen of the present invention can provide a highcontrast of image, and therefore can present a clear image even in abright place. The production of the projection screen is easier thanthat in the case where black stripes are used, and results in a higheryield percentage of quality products.

§3 Third Embodiment of Reflection Type Projection Screen 3.1 FundamentalConstitution

A third embodiment of the reflection type projection screen according tothe present invention will be described with reference to FIGS. 9-11.

As shown in FIG. 9, the fundamental constitution of this reflection typeprojection screen of the present invention includes a number of smallopenings provided at least at a position of a speaker in a flexiblesheet.

In detail, a specific embodiment of the reflection type projectionscreen of the present invention is provided in order, as seen in FIG. 9,showing a cross section, on a light absorbing layer 205 of a darkplastic sheet, with a fibrous sheet 204 having a flexibility, areflection sheet 202, 203 having a base material sheet 203 of a white,opaque, flexible plastic and a reflection layer 202 printed with an inkcontaining a lustrous pigment or calcite powder, and a light diffusinglayer 201 of a translucent, flexible plastic containing a lustrouspigment or calcite powder, in which a convexo-concave emboss 209 isprovided on the outer surface of the light diffusing layer 201, as seenin FIG. 11 showing the entire screen. Numerous small openings 208 areprovided at least at a position of a speaker 212 located behind thescreen to allow sounds from the speaker 212 to pass therethrough. Astiff base plate may replace the flexible fibrous sheet 204. Also, lightabsorbing stripes 211 may be provided at positions corresponding toconcave portions 209a of the emboss 209 on the surface of the reflectionlayer 202 adjoining the light diffusing layer 201.

The plastics used for the base material sheet 203 and for the lightdiffusing layer 201 may be any of flexible plastics, for example,specifically a polyvinyl chloride, in addition, a polyolefin such as apolypropylene and a polyethylene, a polyester such as polyethyleneterephthalate, a polycarbonate, or an acrylic resin. Specifically, asoft material in which a plasticizer is added by 50-60 parts by weightto 100 parts by weight of polyvinyl chloride is preferable. Boththicknesses of the base material sheet 203 and of the light diffusinglayer 201 are between 0.05 and 1 mm.

A sheet formed by kneading a white pigment and a lustrous pigment in aplastic may be used as the base material sheet 203. It is, however,difficult to obtain a plastic in which a large amount of coarse grainsof lustrous pigment are uniformly dispersed. Further, it is notadvantageous to use a large amount of expensive lustrous pigment. Inaddition, such a sheet has a low flexibility. Thus, printing with an inkcontaining the lustrous pigment on a sheet formed by kneading only thewhite pigment therein is advantageous. Titanium dioxide (titanium white)is most preferable as the white pigment with respect to whiteness degreeand to degree of opacity power, but antimony trioxide and zinc white mayalso be employed.

The ink used to form the reflection layer 202 printed on the basematerial sheet 203 is an ink in which a lustrous pigment or calcitepowder is dispersed in a normal ink vehicle (as will be referred to as"sheen ink"). Examples of the lustrous pigment are as follows: (a)materials called pearl pigments, specifically, ground inside portion ofseashells, ground pearl, mica, finely divided particles of mica withTiO₂ or ion oxide baked thereon; (b) metal powders, specifically,copper, aluminum, brass, bronze, gold, silver, preferably in the form offinely divided particles of 1-120 μm; (c) splinters of a depositedplastic film, for example a material obtained by depositing a metal aslisted above, normally aluminum, onto a polyethylene terephthalate filmand grinding it.

Although the proportion of the lustrous pigment is preferably as high inthe ink as possible, a too low proportion of the vehicle makes theformation of the print layer difficult on the base material sheet 203.Then, a preferable composition of the ink is 5-50 parts by weight ofvehicle to 100 parts by weight of pigment.

The calcite powder contained in the ink preferably has an average grainsize of 2-20 μm and a size distribution as narrow as possible. Forexample in case of an average grain size of 5 μm, a size distribution issuch that more than 80% by weight is within a range of 3-7 μm. For thesame reason with regard to the lustrous pigment, a preferablecomposition of the ink is 10-100 parts by weight, specifically 10-50parts by weight, of the vehicle to 100 parts by weight of the calcitepowder.

The printing to form the reflection layer 202 may be any one of knowntechniques such as printing methods of the gravure process, the silkscreen process, or the like, and coating methods of the spray coat, rollcoat, or the like. A sufficient thickness of the reflection layer 202 is1 μm or more in a dry state.

The lustrous pigment or the calcite powder added into the plastic forthe light diffusing layer 201 may be those as described above. Theamount thereof is preferably 0.5-10% by weight, specifically about 2% byweight. The light reflection layer 201 is preferably formed by printingwith a coat containing the above-mentioned lustrous pigment for uniformand isotropic reflection of light, but may also be formed by depositinga metal thin layer of aluminum, chromium, or the like on the basematerial sheet 203.

The flexible fibrous sheet 204 is for enhancing the dimensionalstability of the screen. Particularly, when the screen is used as awind-up screen, the fibrous sheet is required to prevent the screenpulled down from sagging. Further, when the screen is unwound forprojection after storage in a wound condition, a remaining curling maycause a projected image to be warped. Thus, the fibrous sheet isrequired to have an ample elastic recovery. A material to satisfy theserequirements is a woven fabric or an unwoven fabric of glass fibers.

Various methods may be considered to make the small openings 208 in theprojection screen of flexible sheet which can be wound up. For example,on a surface of the light diffusing layer 201 of sheet with theaforementioned lustrous pigment incorporated into or coated on a singlemember or a lamination of the above-mentioned plastic base materialsheet 203 and the fibrous sheet 204, a fine convexo-concave emboss 209of graining, lattice, rectangular, or hexagonal cell recesses isprocessed according to necessity by an embossing process over the entiresurface thereof, and the small openings 208 are perforated therethrough.

For a screen of fixed type, a base plate 204 with stiffness, for examplea metal plate, a wood plate, or a plastic plate, is used.

The plastic sheet for the light absorbing layer 205 is one obtained bykneading a dark, for example, black, dark brown, or dark blue, pigmentsuch as an aniline black, a carbon black, and a red oxide in a plasticmaterial, and by forming it. The thickness of the light absorbing layer205 is preferably equal to the total thickness of the reflection sheet202, 203 and the light diffusing layer 201, balancing the screen in thedirection of thickness.

The above screen can be produced by sandwiching the fibrous sheet 204 orthe base plate between the plastic sheet for the light absorbing layer205 and the lamination of the reflection layer 202 and the lightdiffusing layer 201, consolidating these materials with heat andpressure, and simultaneously making the emboss on the surface of thelight diffusing layer 201. The integrally consolidating may be carriedout by the fusion bonding process or by the dry laminate process.

The lamination of the reflection sheet 202, 203 and the light diffusinglayer 201 can be carried out by laminating the plastic sheet for thelight diffusing layer 201 on the reflection sheet 202, 203, or, bycoating a sol of the plastic for the light diffusing layer 201 on thereflection sheet 202, 203.

The size of the small openings 208 provided in the screen is preferablybetween 0.5 and 2.0 mm in diameter. A too high opening proportion willmake the openings conspicuous for audience and expose the rear sidewhile a too low opening proportion will make the sounds difficult topass therethrough. Thus, a preferable opening proportion is between 15and 65%, specifically between 30 and 50%. The "opening proportion" isthe proportion of total area of the small openings to the area of theportion of the screen through which the sounds pass. The shape of thesmall openings is preferably a circle or an ellipse, which is resistantto tearing when the screen is pulled.

The small openings 208 could be provided over the entire surface of thescreen. If the position of the speaker 212 located behind the screen isfixed as in a fixed screen, the small openings may be made only in aportion facing the speaker 212.

The perforation of the screen is carried out by punching with a cuttingdie, drilling, or melting with CO₂ laser.

The pattern of the emboss 209 may be a pattern with waves intersectingat 90 degrees, which is often used in conventional reflection typeprojection screens. Also, the pattern of the emboss may be arbitrarilychosen from a graining look, a hairline look, or the like.

A modification embodiment of the reflection type projection screen ofthe present invention is provided in order on a non-printed surface of abase material sheet 203 of a white, opaque, flexible plastic having alight absorbing layer 206 which is a solid print layer of a dark ink, asshown in FIG. 10, with one 204 of a flexible fibrous sheet or a stiffbase plate, and a reflection layer 202 of an ink containing a lustrouspigment or calcite powder on a lower surface of a translucent, flexibleplastic sheet 201 for a light diffusing layer into which a lustrouspigment or calcite powder is incorporated, in which an emboss 209 isprovided on the outer surface of the light diffusing layer 201. Further,a number of small openings like pin holes 208 are provided at least at aposition of a speaker 212, through which the sounds from the speaker 212located behind the screen may pass. Also, light absorbing stripes 211are provided at positions corresponding to concave portions 209a of theemboss 209 on the surface of the reflection layer 202 on the side of thelight diffusing layer 201. That is, since the projection light entersthe projection screen near the normal line, the concave portions 209aare regions other than those on which the projection light is converged.

The same materials as described above may be used for the base materialsheet 203, for the fibrous sheet or the base plate 204, for thetranslucent plastic sheet, and for the pigment. The small openings 208made through the screen are also similar to those as described above.The light absorbing layer 206 may be formed using a normal printing in aknown technique such as the gravure process and the screen process. Theproduction of the screen may be carried out in the same manner asdescribed above, i.e., by sandwiching the fibrous sheet or the baseplate 204 between the base material sheet 203 and the translucentplastic sheet 201, 202, compounding them with heat and pressure, andsimultaneously imparting the emboss 209.

An outer frame 210 is printed as shown in FIG. 11 by a suitable methodsuch as silk screen printing on the surface of the reflection typeprojection screen of the present invention as shown in FIGS. 9 and 10.Such a procedure is effective for trimming of the image at the edge,presenting a clearer picture plane. Therefore, this is the methodrecommended.

3.2 Operation

The projection screen of the present invention has the numerous smallopenings 208, which enable sounds to easily passing therethrough. Suchsmall openings prevent the sounds from the speaker 212 from beingconfined, to transmit them before the screen, increasing the power fromthe picture plane. Selecting the size, the shape, and the openingproportion of the small openings 208, the influence thereof on an imagecan be minimized.

3.3 Specific Examples Example 1

A white PVC calender sheet (DOP: 60 phr) of a thickness of 0.13 mm wasemployed as a base material sheet 203. A sheen ink with a composition asdescribed below was printed thereon by the gravure process in a drythickness of 3 μm to obtain a reflection sheet 202, 203 having areflection layer 202.

    ______________________________________                                        Sheen Ink                                                                     ______________________________________                                        Vehicle (PVC)        100 parts by weight;                                     Pigment (titanium coating mica)                                                                     20 parts by weight.                                     ______________________________________                                    

A black PVC sheet (containing 60 phr of DOP as a plasticizer) of athickness of 0.28 mm was employed as a light absorbing layer 205.Superimposed thereon in order were a fibrous sheet 204 of glass fiberwoven fabric, the above reflection sheet 202, 203, a translucent PVCsheet 201 (DOP: 60 phr) of a thickness of 0.15 mm formed by kneadingabout 2% by weight of pearl pigment (titanium coating mica) in PVC andextruding it, and an emboss plate of graining look. These materials wereintegrally bonded and embossed by heat press doubling.

The lamination was blanked by pressing to make small openings 208 ofcircular section in diameter of 0.5 mm at an opening proportion of 55%over the entire surface of the screen, thereby obtaining a projectionscreen of the present invention. This specific Example 1 corresponds tothe reflection type projection screen as shown in FIG. 9.

Example 2

A white PVC calender sheet of thickness of 0.20 mm as a base materialsheet 203, a base plate 204 made of an acrylic resin of thickness of 5mm, and a translucent PVC sheet 201 of thickness of 0.20 mm as inExample 1 were prepared.

A black ink using a pigment of carbon black or the like was printed as asolid print on the base material sheet 203 to form a light absorbinglayer 206. Superimposed on a non-printed surface of the base materialsheet 203 were the base plate 204, and the translucent sheet 201provided with the reflection layer of thickness of 5 μm printed with thesheen ink of Example 1 in such a state that the printed face was down.These materials were bonded integrally and embossed on the translucentsheet 201 in the same manner as in Example 1.

The lamination was blanked by pressing to make small openings 208 ofcircular section of a diameter of 0.8 mm at an opening proportion of 40%in portions between the right edge and 40 cm therefrom and between theleft edge and 40 cm therefrom.

An outer frame 210 of black line was printed with an black ink by thesilk screen process with a width of 3 cm on a surface of the screen thusobtained, producing a reflection type projection screen of the presentinvention squared with a length of a diagonal line of 100 inches.

3.4 Effect

The projection screen of the present invention is effective forprojection of a high quality image on a large picture plane with a highluminance, and for a supply of sounds from a speaker located at asuitable position behind the screen to the audience, increasing theon-the-scene feeling. Therefore, the projection screen is suitable foruse in combination of various projection means such as a liquid crystalprojector with an acoustic instrument such as a stereo.

§4 Fourth Embodiment of Reflection Type Projection Screen 4.1Fundamental Constitution

A fourth embodiment of the reflection type projection screen accordingto the present invention will be described with reference to FIGS.12-19.

One embodiment of the reflection type projection screen of the presentinvention is provided in order on a light absorbing layer 305 of a darkplastic sheet, as shown in FIG. 12, with one 304 of a flexible fibroussheet and a stiff base plate, a reflection sheet 302, 303 in which areflection layer 302 is printed with an ink containing a lustrouspigment or calcite powder on an upper surface of a base material sheet303 of a white, opaque, flexible plastic, and a light diffusing layer301 of a translucent, flexible plastic containing a lustrous pigment orcalcite powder, in which an emboss 309 is provided on the outer surfaceof the light diffusing layer 301. A convexo-concave pattern of theemboss 309 may have either no periodicity or such a periodicity that theperiodic direction of the convexo-concave pattern is inclined at 15-75degrees to the direction of period of projection pixels as detailedlater.

A modification embodiment of the reflection type projection screen ofthe present invention is provided in order on a non-printed surface of abase material sheet 303 of a white, opaque, flexible plastic having alight absorbing layer 306 of a solid print layer of a dark ink, as shownin FIG. 13, with one 304 of a flexible fibrous sheet and a stiff baseplate, and a sheet 301, 302 in which a reflection layer 302 of an inkcontaining a lustrous pigment or calcite powder is provided on a lowersurface of a translucent, flexible plastic sheet for a light diffusinglayer 301 into which a lustrous pigment or calcite powder isincorporated, in which an emboss 309 is provided on the outer surface ofthe light diffusing layer 301. A convexo-concave pattern of the emboss309 may have either no periodicity or such a periodicity that a periodicdirection of the convexo-concave pattern is inclined at 15-75 degrees tothe direction of period of projection pixels.

The plastics used for the base material sheet 303 and for the lightdiffusing layer 301 may be any of flexible plastics, for example,specifically a polyvinyl chloride, in addition, a polyolefin such as apolypropylene and a polyethylene, a polyester such as a polyethyleneterephthalate, a polycarbonate, an acrylic resin, etc. Specifically, asoft material is preferable in which a plasticizer is added by about50-60 parts by weight to 100 parts by weight of polyvinyl chloride. Boththicknesses of the base material sheet and of the light diffusing layeris between 0.05 and 1 mm.

A sheet formed by kneading a white pigment and a lustrous pigment in aplastic may be used as the base material sheet 303. However, it isdifficult to disperse uniformly a large amount of coarse grains oflustrous pigment in a plastic. Also, it is not advantageous to use alarge amount of expensive lustrous pigment. Further, such a sheet has alow flexibility. Thus, it is advantageous that an ink containing alustrous pigment be printed on a sheet formed by kneading only a whitepigment in a plastic. One of most preferable white pigments is titaniumdioxide (titanium white) in respect of whiteness degree and opacifyingpower, but antimony trioxide, zinc white and others may also beemployed.

The ink to form the reflection layer 302 printed on the base materialsheet 303 is an ink in which a lustrous pigment or calcite powder isdispersed in an ordinary ink vehicle (as will be referred to as "sheenink"). Examples of the lustrous pigment are as follows: (a) materialscalled pearl pigments, specifically, ground inside portion of seashells,ground pearl, mica, finely divided particles of mica with TiO₂ or ionoxide baked thereon; (b) metal powders, specifically, copper, aluminum,brass, bronze, gold, silver, preferably, of finely divided particles of1-120 μm; (c) splinters of deposited plastic film, for example amaterial obtained by depositing a metal as listed above, ordinarilyaluminum, onto a polyethylene terephthalate film and grinding it.

Although it is preferable that the proportion of the lustrous pigment inthe ink to form the reflection layer 302 is as high as possible, a toolow proportion of the vehicle makes the formation of the print layerdifficult on the base material sheet 303. Thus, the composition of theink is preferably 5-50 parts by weight of the vehicle to 100 parts byweight of the pigment.

The calcite powder contained in the ink preferably has an average grainsize of 2-20 μm and a size distribution as narrow as possible. Forexample, in case of an average grain size of 5 μm, the size distributionis such that more than 80% by weight fall within a range of 3-7 μm. Forthe same reason as above, the composition of the ink is preferably10-100 parts by weight, specifically 10-50 parts by weight, of vehicleto 100 parts by weight of calcite powder.

The printing to form the reflection layer 302 may be carried out by aknown technique such as a printing method of the gravure process, thesilk screen process, or the like, and a coating method of the spraycoat, the roll coat, or the like. A sufficient thickness of the printlayer is 1 μm or more in a dry state.

The lustrous pigment or the calcite powders added into the plastic forthe light diffusing layer 301 may be the same as above. A preferabledispersion amount thereof is 0.5-10% by weight, specifically about 2% byweight. The light reflection layer 301 is preferably formed by printcoating with a coat containing the above-mentioned lustrous pigment inrespect of uniform and isotropic reflection of light. The lightreflection layer 301 may be also formed by depositing a metal thin layerof aluminum, chromium, or the like on the base material sheet.

The flexible fibrous sheet 304 is for enhancing the dimension stabilityof the screen. Particularly, when the screen is used as a wind-upscreen, the fibrous sheet is required to prevent the screen pulled downfrom sagging. Also, when the screen is unwound in use for projectionafter storage in a wound condition, a remaining curling may cause animage projected to be warped. Therefore, the fibrous sheet is requiredto have a sufficient elastic recovery. A material to satisfy theserequirements is a woven fabric or an unwoven fabric of glass fibers.

For a screen of fixed type, the stiff base plate 304 may be for examplea metal plate, a wood plate, or a plastic plate.

The plastic sheet for the light absorbing layer 305 is obtained byincorporating a dark, for example, black, dark brown, or dark blue,pigment, for example, an aniline black, a carbon black, or a red oxide,into the plastic material as in the case of the base material sheet. Thethickness of the sheet is preferably equivalent to the total thicknessof the reflection sheet 302, 303 and the light diffusing layer 301,which balances the screen in the direction of thickness.

The above screen can be produced by sandwiching one 304 of the fibroussheet and the base plate between the plastic sheet for the lightabsorbing layer 305 and the lamination of the reflection layer 302 andthe light diffusing layer 301, consolidating them with heat andpressure, and simultaneously imparting an emboss on the surface of thelight diffusing layer 301. The consolidation may be carried out byeither the fusion bonding method or the dry laminate method.

The lamination of the reflection sheet 302, 303 and the light diffusinglayer 301 may be conducted by laminating the plastic sheet for the lightdiffusing layer 301 on the reflection sheet 302, 303, or, by coating asol of the plastic for the light diffusing layer 301 on the reflectionsheet.

A preferable pattern of the emboss 309 is a satin, a graining, or ahairline, which has no periodicity in convexo-concave pattern. Thepattern may be a pattern with waves intersecting at 90 degrees, which isoften used in conventional reflection type projection screens, or apattern in which lattice, rectangular, or hexagonal cell recessescontinue. In the case where the convexo-concave pattern has such aperiodicity, the periodic direction of the convexo-concave pattern mustbe inclined at 15-75 degrees to the periodic direction of projectionpixels, as described above.

In another modification embodiment as shown in FIG. 13, a lightabsorbing layer 306 is formed using a normal printing by a knowntechnique such as the gravure process, the screen process, and the like.The production of the screen may be conducted in the same manner asabove, i.e., by sandwiching one 304 of a fibrous sheet and a base platebetween a base material sheet 303 having a light absorbing layer 306 anda translucent plastic sheet 301 having a reflection Layer 302,consolidating them with heat and pressure, and simultaneously making anemboss 309 thereon.

As shown in FIG. 14, an outer frame 310 of a dark ink is printed by asuitable method such as silk screen printing on a surface of the lightdiffusing layer 301 in the reflection type projection screen of thepresent invention. The outer frame 310 produces a proper trimming on animage at the edge, making the picture plane clearer. Thus, this is therecommended arrangement.

For a need to enhance the on-the-scene feeling in use of the projectionscreen, a speaker may be set behind the screen and numerous smallopenings may be provided at a position of the speaker in the screen. Thesize of the small openings made in the screen is preferably between 0.5and 2.0 mm in diameter. A too high opening proportion makes the openingsoutstanding for audience as to look through the screen while a too lowopening proportion makes sounds difficult to pass therethrough. Thus, apreferable opening proportion is between 15 and 65%, specificallybetween 30 and 50%. The "opening proportion" is a proportion of thetotal area of the small openings relative to the area of the portion ofthe screen through which sounds pass. The shape of the small openings ispreferably a circle or an ellipse, which is resistant to tearing whenthe screen is pulled. The small openings may be provided over the entiresurface of the screen if desired. Also, if the position of the speakeris fixed behind the screen as in a screen of fixed type, the smallopenings may be provided only at the portion facing the speaker. Theperforation of the screen may be carried out by means of punching with acutting die, drilling, or melting with CO₂ laser.

Also, in FIGS. 12 and 13, light absorbing stripes 311 are provided atpositions corresponding to concave portions 309a of the emboss 309 onthe surface of the reflection layer 302 on the side of the lightdiffusing layer 301. In other words, the concave portions 309a areregions other than those on which the projection light is converged,because the projection light enters the projection screen near thenormal line thereof.

The pattern of the emboss 309 formed on the surface of the lightdiffusing layer 301 will be next described with reference to FIGS.14-19. In detail, if the convexo-concave pattern of the emboss 309 has aperiodicity, the periodic direction of the convexo-concave pattern isinclined at an angle of 15-75 degrees to the arrangement direction ofprojection pixels. Or, the convexo-concave pattern of the emboss 309 maynot have a periodicity.

FIGS. 14-16 are drawings to show a case in which the convexo-concavepattern of the emboss 309 has a periodicity. In FIG. 14, the emboss 309comprises concave portions 309a positioned with a periodicity andportions 309b (convex portions) excluding the concave portions 309a. Onthe reflection type projection screen, the concave portions 309a of theemboss 309 are arranged with a periodicity and the periodic direction isthe x direction in the x-y coordinates in FIG. 14. Also, in FIG. 15,numeral 315 denotes a picture plane to be projected on the reflectiontype projection screen. The picture plane 315 comprises a number ofprojection pixels 316, and the arrangement direction of the projectionpixels 316 is the X direction on the X-Y coordinates in FIG. 15.

FIG. 16 is a superposition of the x-y coordinates in FIG. 14 and the X-Ycoordinates in FIG. 15. As shown in FIG. 16, the x-y coordinates and theX-Y coordinates are inclined to each other by θ. The inclination angle θis set as follows:

    15°≦θ≦75°.

Next, a case in which the convexo-concave pattern of the emboss 309 doesnot have a periodicity will be described with reference to FIGS. 17-19.As shown in FIGS. 17 and 18, the emboss 309 of the convexo-concavepattern without a periodicity is formed on the outer surface of thelight diffusing layer 301. Such a convexo-concave pattern is called asatin pattern, a graining pattern, or the like.

FIG. 19 shows the surface pattern of the emboss 309. FIG. 19 is across-sectional view along line A-B in FIG. 17. As shown in FIG. 19, theconvexo-concave pattern without a periodicity may be formed using arandom convexo-concave surface which is formed by ground glass, sandshardened to give a plane surface, a tracing paper, or a suede (a kind ofleather). A central line average roughness of the convexo-concavepattern is preferably about 5-500 μm.

4.2 Operation

The picture plane 315 of a liquid crystal television has numerousprojection pixels 316 of rectangle periodically repeated in the verticaland the horizontal directions, which is to be projected onto aprojection screen. If the emboss 309 formed on the surface of theprojection screen has a pattern with concave portions of rectanglesperiodic in the horizontal and the vertical directions and with the sameperiodic direction as the arrangement direction of the projection pixels316 (for example as disclosed in Japanese Laid-open Utility ModelPublication No. Sho 64-40835), which has been used for movies, moirefringes would appear due to a mutual action between the projected pixels316 and the convexo-concave pattern of the emboss 309 on the screen.This is a cause of loss of clearness of image.

The above problem will be solved by using a pattern with no periodicity,for example, a pattern of the satin or the graining as described above,for the convexo-concave pattern of the emboss 309 as in the presentinvention. Even with a periodicity, if the direction of period of theconvexo-concave pattern of the emboss 309 is not in parallel with thearrangement direction of the pixels 316, or, if they are inclined tosome extent to each other, the mutual interference is unlikely to occur,not causing the moire fringe phenomenon. This extent is an inclinationof at least 15 degrees as described above. The upper limit of 75 degreesis determined because most convexo-concave patterns have bidirectionalperiods intersecting at an angle of 90 degrees and because oneinclination over 75 degrees results in lowering the other inclinationbelow 15 degrees. It is in general preferable that the inclination beset at 30 degrees or at 45 degrees to assure the above effect.

4.3 Specific Examples Example 1

A white PVC calender sheet (DOP: 60 phr) of a thickness of 0.13 mm wasused as a base material sheet 303. A reflection sheet 302, 303 wasobtained by printing a reflection layer 302 with a sheen ink with acomposition as described below by the gravure printing in a drythickness of 3 μm on the PVC sheet.

    ______________________________________                                        Sheen Ink                                                                     ______________________________________                                        Vehicle (PVC)        100 parts by weight;                                     Pigment (titanium coating mica)                                                                     20 parts by weight.                                     ______________________________________                                    

A black PVC sheet (containing 60 phr of DOP as a plasticizer) of athickness of 0.28 mm was used as a light absorbing layer 305.Superimposed in order thereon were a fibrous sheet 304 of glass fiberwoven fabric, the above reflection sheet 302, 303, a translucent PVCsheet 301 (DOP: 60 phr) of a thickness of 0.15 mm formed by kneadingabout 2% by weight of a pearl pigment (titanium coating mica) in aplastic and extruding it, and an emboss plate of graining look. Thematerials were consolidated and embossed by heat press doubling.

The projection screen of the present invention thus obtained had peakgains of 2.16 in the vertical direction and of 1.84 in the horizontaldirection. When an image of a liquid crystal television was projectedonto the projection screen, a clear reflection image was observedthereon. This specific Example 1 corresponds to the reflection typeprojection screen as shown in FIG. 12.

Example 2

A white PVC calender sheet of a thickness of 0.20 mm as a base materialsheet 303, a base plate 304 made of an acrylic resin of a thickness of 5mm, and a translucent PVC sheet 301 of a thickness of 0.20 mm wereprepared similarly as in Example 1.

A solid print was applied on the base material sheet 303 with a blackink using a pigment of a carbon black or the like to form a lightabsorbing layer 306. On a non-printed surface of the base material sheet303 were superimposed the base plate 304 and the translucent sheet 301provided with the reflection layer 302 of a thickness of 5 μm with thesheen ink of Example 1 in such a state that the reflection layer 302 wasdown. These materials were bonded together and embossed in the samemanner as in Example 1. The emboss had line projections parallel to eachother at a fine pitch, between which line projections, which were highat both ends and slightly low at the center, connected. The direction ofthe pattern was inclined at 45 degrees.

An outer frame 310 of a black line of a width of 3 cm was made by thesilk screen printing with a black ink on the surface of the screen thusobtained, producing a reflection type projection screen of the presentinvention squared with a length of a diagonal line of 100 inches. Aclear image was also observed as projected from a liquid crystalprojector onto this screen. This specific Example 2 corresponds to thereflection type projection screen shown in FIG. 13.

4.4 Effect

The projection screen of the present invention can always provide aclear image without the nuisance of moire fringes when an image with anassembly of pixels repeated with a periodicity is projected. Inaddition, of course, the projection screen is useful for watchingordinary movies.

§5 First Embodiment of Production Process of Reflection Type ProjectionScreen 5.1 Fundamental Constitution

A first embodiment of the production process of the reflection typeprojection screen according to the present invention will be describedwith reference to FIGS. 20-25.

This embodiment of the production process of the reflection type screenof the present invention comprises the following steps. In detail, asshown in FIG. 20, the steps are of rotating a rotary intaglio (masterroll) 405 having a surface of fine convexo-concave pattern in lens form,of filling at least recess portions 415 of the rotary intaglio 405 withan ionizing radiation curing resin liquid 413 from a nozzle 416, and ofurging a support sheet 411 of a transparent, flexible plastic running inthe rotation direction of the rotary intaglio 405 in synchronismtherewith, against the rotary intaglio 405 by a press roll 406. Thesupport sheet 411 is thereafter fed downstream by a lead-on roll 407.

Then, as shown in FIG. 20, the rotary intaglio 405 is rotated while thesupport sheet 411 is kept in contact with the rotary intaglio 405. Anionizing radiation is irradiated from ionizing radiation irradiatingmeans 408 to cure the ionizing radiation curing resin liquid 413, andsimultaneously to cause the cured resin layer 412 and the support sheet411 to adhere to each other. Then, the support sheet 411 is separatedtogether with the cured resin layer 412 from the rotary intaglio 405,whereby a lens sheet 401 is produced, in which the fine convexo-concavecured resin layer 412 is formed in lens form on one face of the supportsheet 411. Then, backing base materials 402, 403, 404 with properties ofdiffusion and reflection of light are laminated on the non-lens surfaceof the lens sheet 401, as shown in FIG. 22.

A modification embodiment of the production process of the reflectiontype screen of the present invention comprises the following steps.Namely, as shown in FIG. 21, there is a step of urging against therotary intaglio 405 the support sheet 411 of a flexible plasticpreliminarily coated with the ionizing radiation curing resin liquid 413by coating means 419 so as to keep the coated surface in contact withthe rotary intaglio 405.

Then, the rotary intaglio 405 is rotated while the support sheet 411 iskept in contact with the rotary intaglio 405. The ionizing radiation isirradiated from the ionizing radiation irradiating means 408 to cure theionizing radiation curing resin liquid 413, and simultaneously to causethe cured resin layer 412 and the support sheet 411 to adhere to eachother. Thus a lens sheet 401 is produced, in which the fineconvexo-concave cured resin layer 412 is formed in lens form on one faceof the support sheet 411. Then, backing base materials, 402, 403, 404with properties of diffusion and reflection of light are laminated onthe non-lens surface of the lens sheet 401, as shown in FIG. 22.

In FIG. 20, when the ionizing radiation curing resin liquid is suppliedto fill each recess portion 415 of the rotary intaglio 405, the resin issupplied at a position where the support sheet 411 is urged against therotary intaglio by the press roll 406 (between the rotary intaglio 405and the press roll 406), whereby the resin fills the recess portion 415with the rotation of the rotary intaglio 405. A more preferabletechnique is to fill each recess portion 415 of the rotary intaglio 405with the resin liquid by using a nozzle 416 of T die type, which canreadily prevent gas bubbles from entering the resin layer 412.

A most preferable production apparatus has an arrangement as shown inFIG. 24. This apparatus will be described with reference to FIG. 24 (A).A rotary intaglio 405 is provided with recesses 415 of lens form on acylindrical printing material. The recesses 415 may be made by a methodof direct lathe machining on the cylindrical printing material, by amethod of cutting such as milling with a mill formed by theelectroforming process, or by an electroforming process. Materialsusable for the rotary intaglio 405 are metals such as copper, chromium,ion, and the like, synthetic resins such as NBR, epoxy, ebonite, and thelike, and ceramics such as glass. The size of the rotary intaglio 405 isnot specifically limited and may be suitably determined in accordancewith a size of the screen to be produced. A drive apparatus (not shown)may be provided for the rotary intaglio 405 to rotate the same.

To control the viscosity of the resin liquid 413 at a predeterminedvalue, as seen in rotary intaglios 405A-405D as shown in FIG. 25, amethod may be employed to make the rotary intaglios 405A-405D hollowinside, to introduce and discharge a fluid as a heating medium such aswater, oil, vapor and the like at an appropriate temperature, and tocontrol the surface temperature of the intaglios at a suitable value.The viscosity of the resin liquid 413 decreases in general as it becomeshotter. A too high temperature causes decomposition or vaporization ofthe resin liquid 413. Therefore, a preferable temperature is about15-50° C., though depending upon the resin.

Various arrangement as shown in FIG. 25 may be employed to introduce anddischarge the fluid into and out of the rotary intaglios 405A-405D.Specifically, there is a method in which the fluid is forced to flowfrom one side to the other side of a rotation shaft 405a of the rotaryintaglio 405A as shown in FIG. 25 (A). Also, there is a method as shownin FIG. 25 (B) in which a feed pipe 405b is inserted inside the rotaryintaglio 405B, and the fluid is first fed through the feed pipe 405b toa fore end inside the rotary intaglio 405B and then returned along theinternal wall surface of the rotary intaglio 405B. Further, there is amethod as shown in FIG. 25 (C) in which an inner pipe 405C' having afigure similar to the rotary intaglio 405C is disposed inside the rotaryintaglio, and the fluid is forced to flow between the rotary intaglio405C and the inner pipe 405C'. Further, there is a method as shown inFIG. 25 (D) in which a feed pipe 405d with numerous openings 405e asshown in FIG. 25 (E) is inserted inside the rotary intaglio 405D, andthe fluid ejected from the openings 405e of the feed pipe 405d isreturned along the internal wall surface of the rotary intaglio 405D.The best method is an arrangement as shown in FIG. 25 (D) to uniformlyadjust the surface temperature of the rotary intaglio.

Returning to FIG. 24 (A), the press roll 406 is for pressing the basematerial sheet 411, which is normally formed of a silicone rubber, anNBR, an EPT, or the like, with a diameter of about 140 mm. The pressroll 406 and the lead-on roll 407 may be arranged to rotate withrotations of the rotary intaglio 405, but are preferably driven byrespective drive devices.

In FIG. 24, another illuminating means 408b may be provided to makecomplete the curing of the ionizing radiation curing resin liquid by theionizing radiation illuminating means 408a. It is desirable as means forcoating the ionizing radiation curing resin liquid 413 on the rotaryintaglio 405 to use a nozzle coating device 416 as shown in FIG. 24 (A).In the nozzle coating device 416, a nozzle of T die type has arectangular or linear discharge pore of a predetermined size to cover apredetermined width out of the entire width of the rotary intaglio, andpressurizing means is provided for dispensing the ionizing radiationcuring resin liquid in a curtain form pressurized, onto the rotaryintaglio 405.

As shown in FIG. 21, the ionizing radiation curing resin liquid 413 maybe applied as a coat on the support sheet 411, instead of being coatedon the rotary intaglio 405, and then the coated surface on the supportsheet 411 is urged by the press roll 406 against the rotary intaglio405. By this method there is no mixing of gas bubbles into the resin. Inorder to reproduce faithfully a fine convexo-concave pattern, it ispreferable that the resin liquid be coated on the rotary intaglio 405.

The ionizing radiation irradiating means 408a near the rotary intaglio405 may be a single unit as shown in FIG. 24 (A), or it may be plural(five of 408a-1 to 408a-5) as shown in FIG. 24 (B) to cure the resinliquid 413 in the rotary intaglio 405 in multiple steps. By such anarrangement, a sufficient irradiation amount can be obtained even at ahigh traveling speed of the support sheet 411. Also, gradual curing ispreferable in that it will reduce strain in the cured object of theresin liquid as well as a curl or a strain in the support sheet 411.

The ionizing radiation curing resin liquid 413 used here is selectedfrom known resin liquids and preferably has a viscosity below 5000 cps,specifically of about 1000 cps, to readily spread inside the recesses415 of the rotary intaglio 405. The viscosity of the resin liquid 413can be adjusted by selection of a proper monomer, oligomer, orprepolymer, or by changing the temperature of the rotary intaglio 405.It is desirable that the ionizing radiation curing resin liquid 413 beused without a solvent solution if possible. This is because asolventless resin liquid 413 shows no volume contraction or no change inshape upon curing, accurately reproducing the convexo-concave pattern ofthe intaglio on the support sheet.

The ionizing radiation curing resin is a monomer, oligomer, orprepolymer having in its molecule an ethylenically unsaturated bondingor, an epoxy group or a thiol group, specifically, one selected from(meth)acrylates such as an urethane (meth)acrylate and a polyester(meth)acrylate, and unsaturated polyesters. In the case where it is tobe cured by light or ultra violet light, a known photo reactioninitiator is preferably added.

In the arrangement as shown in FIG. 21, the coating of the ionizingradiation curing resin liquid 413 onto the support sheet 411 can becarried out by known coating means 409 such as a roll coater or a knifecoater. In this case, no matter what coating means is used, the coatingis difficult without solvent dilution of the resin. Then, before thesupport sheet 411 is urged against the rotary intaglio 405, a solvent ispreferably volatilized from the coating by heating by means of a heatingapparatus (not shown). If necessary, ionizing radiation may beirradiated onto the support sheet 411 before it is urged against therotary intaglio 405 to make the coating semi-cured so as to adjust theviscosity.

The irradiating means 408, 408a, 408b of the ionizing radiation ispreferably an ultra-violet lamp, for example, a super-high-pressuremercury-vapor lamp, a high pressure mercury-vapor lamp, a low-pressuremercury-vapor lamp, a carbon arc, a black light lamp, or a metal halidelamp, which are simple in operation. Also, electron beam accelerators ofvarious types may be used, for example, a Cockcroft-Walton accelerator,van de Graaff accelerator, a resonance-transformer type accelerator, aninsulating core-transformer type accelerator, a linear accelerator, adynatron type accelerator, a high-frequency type accelerator.

If a material of the support sheet 411 does not readily transmitultra-violet light, for example, if a plastic sheet into which alustrous pigment as described later is incorporated is used, the aboveelectron beam accelerators may be used as the ionizing radiationirradiating means, or, the rotary intaglio 405 may be produced from amaterial such as a quartz glass or glass which transmits the ionizingradiation, and the ionizing radiation may be irradiated from ionizingradiation irradiating means disposed inside the rotary intaglio 405.

The plastics used for the transparent support sheet 411 and for thebacking base materials may be any of flexible plastics. The material forthe support sheet 411 is required to have transparency to a visiblelight, while the material for the base material sheet may be opaque. Arepresentative material is a polyvinyl chloride. Particularly, apreferable material is a semirigid or soft polyvinyl chloride in which aplasticizer is added by about 10-60 parts by weight to 100 parts byweight of polyvinyl chloride. In addition, a polypropylene, apolyethylene, a polyethylene terephthalate, and a polycarbonate may bealso used. The thickness of the support sheet 411 is preferably between25 and 200 mm, while the thickness of the backing base material ispreferably between 50 and 200 mm.

To obtain a high reflectivity and a moderate half-value angle, alustrous pigment as later described may be added by about 0.5-10% byweight in the support sheet 411.

The fine recesses and protrusions 412 on the cured resin layer 412, thatis, on the support sheet 411, may be so formed that the recess portionsand the projection portions will have quadric surfaces or cubic surfacesin shape. Specifically, the surfaces may be (1) a so-called fly eye lenstype reflection concave mirror in which are distributed, for example,spherical surfaces, elliptic surfaces, (portions of) a paraboloid ofrevolution, cones or truncated cones, pyramids or truncated pyramids, orsmall concave mirrors; (2) a lenticular type reflection concave mirrorin which concave mirrors in the shape of a cylinder, a paraboliccylinder, an elliptic cylinder, or those cut into halves along symmetricaxis thereof, are distributed all over the surface so that the verticaldirection is coincident with the axial direction.

If it is desired that the screen be seen with the same luminance fromany direction by isotropically diffusing the light in all directions upand down, right and left, and obliquely, the use of a spherical concavemirror group of (1) is suitable. In contrast, if the screen is forordinary viewing not necessitating a vertical wide view field butnecessitating a horizontal wide view field, the lenticular type concavemirror group of (2) is preferable because it can diffuse light oflimited amount effectively toward necessary portions (in the front, theright, and the left directions). Normally, a light diffusion half-valueangle in the horizontal plane (in the directions of the right and theleft), which is an angle at which the reflectivity reduces to a half tothat in a direction normal to the screen, should be 20 degrees or more,preferably about 60 degrees.

The surface pattern of the cured resin layer 412 can be an embosspattern which is frequently used in conventional reflection typescreens, for example, a pattern with waves intersecting at 90 degrees,or patterns of graining look and of hairline look.

The backing base materials 402, 403, 404 are constituted by laminating,from the side near the support sheet 411, the black or white opaque basematerial sheet 402, the fibrous sheet 403, and the light absorbing layer404 in this order, as shown in FIG. 22. If an especially highreflectivity and an especially narrow light diffusion half-value angleare not required, one or both of the light diffusing layer and the lightreflection layer may be omitted. Also, without such limitation,laminated from the side of the support sheet 411 are the fibrous sheet403, the base material sheet 402, and the light absorbing layer 404 inthis order.

To obtain the white opaque base material sheet 402, a white pigment suchas fine powders of TiO₂ may be kneaded in a plastic for the basematerial sheet 402. Depending upon the reflection amount desired, ablack resin sheet may be alternatively used.

The fibrous sheet 403 is for enhancing the dimensional stability of thescreen. Specifically, if the screen is used as a wind-up screen, thefibrous sheet is required to prevent the screen pulled down fromsagging. Also, if the screen is unwound in use for projection afterstorage in a wound condition, a remaining curling may cause an imageprojected to be warped. Thus, the fibrous sheet 403 is required to haveample elastic recovery and ample stiffness. A material to satisfy theserequirements is a woven fabric or an unwoven fabric of glass fibers.

As shown in FIG. 22, in the case where the light absorbing layer 404 islaminated on the fibrous sheet 403 of glass fibers, laminated as thelight absorbing layer 404 on the fibrous sheet 403 is a sheet obtainedby incorporating a dark, for example, black, dark brown, or dark blue,pigment into the same plastic as the material for the base materialsheet and forming it. The thickness of the sheet 404 is preferablyequivalent to the total thickness of the base material sheet 402 and thesupport sheet 411, balancing the screen in the direction of thickness.

As shown in FIG. 23, if it is desired that the light absorbing layer 404be provided on the base material sheet 402, the light absorbing layer404 can be formed by a solid print with a dark ink on the base materialsheet 402. The printing can be conducted by known means.

The lens sheet 401, the base material sheet 402, and the fibrous sheet403 all may be simultaneously laminated. Alternatively, the basematerial sheet 402 and the fibrous sheet 403 may be first laminated toform a backing sheet, and the lamination and the lens sheet 401 may bethen laminated. The order is arbitrary. The lamination process may bechosen from known techniques such as the dry laminate process and thefusion bonding process.

As shown in FIG. 22, if a clear projected image is desired to be seenunder illumination of light from the sun or from an electric lamp asoptical properties of the screen, one or both of the light diffusinglayer 420 and the light reflection layer 421 should be disposed betweenthe lens sheet 401 and the fibrous sheet 403 or the base material sheet402. The light diffusing layer 420 is a sheet of a translucent, flexibleplastic into which a lustrous pigment or calcite powder is incorporated.The plastic used for the light diffusing layer 420 may be the sameplastic used for the base material sheet or for the support sheet.

Examples of the lustrous pigment are as follows: (a) materials calledpearl pigments, specifically, ground inside portion of seashell, groundpearl, mica, finely divided particles of mica with TiO₂ or ion oxidebeing baked thereon; (b) metal powders, specifically, copper, aluminum,brass, bronze, gold, silver, preferably, of finely divided particles of1-120 μm; (c) splinters of deposited plastic film, for example amaterial obtained by depositing a metal as listed above, ordinarilyaluminum, onto a polyethylene terephthalate film and grinding it. Theselustrous pigments are preferably scaly in shape. If the planes of thescaly bodies are arranged to be in parallel with the surface of the basematerial sheet, irregular reflection can be effected with a highluminance.

The calcite powder preferably has an average grain size of 2-20 μm and asize distribution as narrow as possible. For example, in case of anaverage grain size of 5 μm, the size distribution is such that more than80% by weight fall within a range of 3-7 μm.

The amount of the lustrous pigment or the calcite powders added into theplastic for the light diffusing layer 420 is preferably 0.5-100% byweight, specifically about 2% by weight.

If the reflection layer is not provided, the thickness of the lightdiffusing layer 420 should be preferably between 0.04 and 0.8 mm, takingit into consideration that attenuation of reflection light amount is tobe restricted to keep the projected image brighter. If the reflectionlayer is provided, the attenuation of the reflection light amount is lowso that the thickness of the light diffusing layer is preferably between0.05 and 1 mm, taking into consideration that the half-value angle israther to be broadened by increasing the thickness of the lightdiffusing layer.

The lamination of the light diffusing layer 420 may be carried out inthe same manner as that of other sheets. The support sheet may serve asthe light diffusing layer, using a support sheet in which the abovelustrous pigment or calcite powder is dispersed.

The light reflection layer 421 is provided by a solid print with an inkcontaining a lustrous pigment or calcite powder on the light diffusinglayer 420 or the base material sheet 402 before the lamination of therespective sheets.

The ink used for printing of the light reflection layer 421 is an ink inwhich a lustrous pigment or calcite powder is dispersed in an ordinaryink vehicle. Examples of the vehicle are polyvinyl chlorides, polyvinylchloride-polyvinyl acetate copolymers, acrylic resins, polyurethanes,and polyesters.

Although the rate of the lustrous pigment in the ink is preferably ashigh as possible, a too low rate of the vehicle makes difficult theformation of the print layer on the base material sheet. Thus, thecomposition of the ink is preferably 5-50 parts by weight of vehicle to100 parts by weight of pigment. The thickness coated by printing isnormally about 1-10 μm.

The ink in which such grains of lustrous pigment are dispersed tends tocause unevenness in printing. Thus, instead of a single printing toobtain a desired thickness, it is preferable to obtain a high reflectionproperty of the light diffusing layer by a process comprising a step ofprinting a fraction of the desired thickness and repeating this step toobtain the total thickness desired in layers thereafter.

If the calcite powder is used, the composition of the ink, for the samereason as above, is preferably 10-100 parts by weight, specifically10-50 parts by weight, of the vehicle to 100 parts by weight of thecalcite powder.

The printing method may be one of known techniques, for example,printing methods such as the gravure process and the silk screenprocess, and coating methods such as the spray coat and the roll coat. Asufficient thickness of the print layer is 1 μm or more in a dry state.

5.2 Operation

The present invention employs, as a measure for forming a fineconvexo-concave pattern on the surface of the screen, a method in whichthe ionizing radiation curing resin 413 is placed on the support sheet411 in use of the rotary intaglio 405 in a printing manner, replacingthe conventional embossing process. According to this method, since theconvexo-concave pattern is formed with the fluid non-cured resin 413,and the resin is cured in a state controlled by the rotary intaglio 405,the fine convexo-concave pattern of the ionizing radiation curing resincan be formed on the support sheet 411 while accurately reproducing thepattern on the intaglio, consequently producing a reflection type screenwith desired optical properties.

The production method of the present invention affords high productivitywith continuous production of lens sheet as compared to a method ofembossing screens one by one.

5.3 Specific Example

A rotary intaglio 405 of copper was prepared by forming a reversedconvexo-concave pattern of the lenticular lens type by theelectroforming process and chromium deposition on a surface thereof. Asshown in FIG. 24, there were assembled a nozzle coating device 416 forfilling recesses 415 of the rotary intaglio 405 with an ionizingradiation curing resin liquid 413, a press roll 406 for urging thesupport sheet 411 against the rotary intaglio 405, and a lead-on roll407 for separating the support sheet 411 from the rotary intaglio 405,and five rows of high-pressure mercury-vapor lamps of two-lampozonization type (intensity 120 W/cm) were disposed in the rotationdirection of the rotary intaglio 405 as ionizing radiation irradiatingmeans 408a between the press roll 406 and the lead-on roll 407.

A colorless transparent sheet of biaxially oriented polyethyleneterephthalate of a thickness of 25 μm was used as the support sheet 411.An ultra-violet curing resin liquid (ionizing radiation curing resinliquid) 413 (solventless type, viscosity of 1000 cps) containing as amain ingredient polyester acrylate polyfunctional monomers was appliedthereon using the above device, thereby producing a lens sheet 404having the cured resin layer 421 formed in lenticular lens pattern.

A black polyvinyl chloride sheet (DOP: 60 phr) of a thickness of 0.2 mmwas used as the light absorbing layer 404 disposed on a back face of afibrous sheet, and a woven fabric of glass fibers was used as thefibrous sheet 403. A white polyvinyl chloride sheet (DOP: 60 phr) of athickness of 0.13 mm was used as the base material sheet 402 and atranslucent sheet of thickness of 0.12 mm which was obtained by kneading2% by weight of pearl pigment (titanium coating mica) in a polyvinylchloride (DOP: 60 phr) and extruding it was used as the light diffusinglayer.

The fibrous sheet 403, the base material sheet 402, and the lightdiffusing layer 420 were superimposed in order on the above lightabsorbing layer 404. These layers were integrally laminated by a heatpress doubling process using a mirror plate laminate roll.

The above-mentioned lens sheet 401 was laminated on the light diffusinglayer 420 of this lamination by the dry laminate process using atwo-part liquid curing polyurethane adhesive, thereby obtaining areflection type screen of the present invention by cutting into apredetermined size.

5.4 Effect

According to the method of the present invention, a reflection typescreen can be produced with desired optical properties. The productionprocess has high productivity and therefore advantageous in cost, ascompared to that by the conventional emboss method.

§6 Second Embodiment of Production Process of Reflection Type ProjectionScreen 6.1 Outline of Reflection Type Projection Screen

A second embodiment of production process of the reflection typeprojection screen according to the present invention will now bedescribed with reference to FIGS. 26 to 30.

An outline of the reflection type projection screen will be firstdescribed with reference to FIGS. 26 to 28. FIGS. 26 and 27 show anembodiment of the reflection type projection screen. In FIGS. 26 and 27,the projection screen is provided in order on a light absorbing layer555 of a dark plastic sheet, with a fibrous sheet 554 of glass fibers, abase material sheet 553 of a white, opaque, flexible plastic, areflection layer printed with an ink containing a lustrous pigment orcalcite powder, and a light diffusing layer 551 of a translucent,flexible plastic into which a lustrous pigment or calcite powder isincorporated, in which an emboss 559 is provided on the outer surface ofthe light diffusing layer 551. Among these layers, the reflection layer552, the base material sheet 553, the fibrous sheet 554, and the lightabsorbing layer 555 constitute a backing base material of lightdiffusion and reflection type.

The plastics used for the base material sheet 553 and for the lightdiffusing layer 551 may be any of flexible plastics, for example,representatively a polyvinyl chloride, in addition, a polypropylene anda polyethylene. Specifically, a soft material is preferable, in which aplasticizer is added by about 50-60 parts by weight to 100 parts byweight of polyvinyl chloride. The thickness of the base material sheet553 may be between 0.05 and 1 mm.

Examples of the lustrous pigment mixed into the light diffusing layer551 and the reflection layer 552 are as follows: (a) materials calledpearl pigments, specifically, ground inside portion of seashells, groundpearl, mica, finely divided particles of mica with TiO₂ or ion oxidebaked thereon; (b) metal powders, specifically, copper, aluminum, brass,bronze, gold, silver, preferably, of finely divided particles of 1-120μm; (c) splinters of deposited plastic film, for example a materialobtained by depositing a metal as listed above, normally aluminum, ontoa polyethylene terephthalate film and grinding it. These lustrouspigments are preferably scaly in shape. Planes of the scaly bodies arepreferably arranged to be in parallel with the surface of the basematerial sheet, producing irregular reflection with a high luminance.

The calcite powder mixed into the light diffusing layer 551 and thereflection layer 552 preferably has an average grain size of 2-20 μm anda size distribution as narrow as possible. For example, in case of anaverage grain size of 5 μm, the size distribution is such that more than80% by weight fall within a range of 3-7 μm.

The amount of the lustrous pigment or the calcite powder added to theplastic for the light diffusing layer 551 is preferably 0.5-10% byweight, particularly, about 2% by weight.

The ink used for forming the reflection layer 552 by printing onto thebase material sheet 555 is an ink in which the lustrous pigment or thecalcite powder is dispersed in an ordinary ink vehicle. Examples of thevehicle are polyvinyl chlorides, polyvinyl chloride-polyvinyl acetatecopolymers, acrylic resins, polyurethanes, and polyesters. Although theproportion of the lustrous pigment in the ink is preferably as high aspossible, a too low proportion of the vehicle makes the formation of thereflection layer 552 on the base material sheet 553 difficult. Apreferable composition of the ink is 5-50 parts by weight of the vehicleto 100 parts by weight of the pigment. The thickness coated by printingis ordinarily about 1-10 μm.

The ink in which such grains of lustrous pigment are dispersed tends tocause unevenness in printing. Thus, instead of a single printing toobtain a desired thickness, it is preferable to obtain a high reflectionproperty of the light diffusing layer 551 by repetitive printings eachof a fraction of the thickness desired to obtain the desired thicknessin layers.

If the calcite powder is used, the composition of the ink, for the samereason as above, is preferably 10-100 parts by weight, particularly10-50 parts by weight, of the vehicle to 100 parts by weight of thecalcite powder.

The printing may be carried out by one of the known techniques, forexample, printing methods such as the gravure process or the silk screenprocess, and coating methods such as the spray coating or the rollcoating. A sufficient thickness of the print layer is 1 μm or more in adry state.

If the reflection layer 552 is not provided, a thickness of the lightdiffusing layer 551 is preferably between 0.04 and 0.8 mm, taking intoconsideration that an attenuation amount of reflection light is kept assmall as possible to maintain a projected image brighter. If thereflection layer 552 is provided, the attenuation amount of reflectionlight is little, and therefore the thickness is preferably between 0.05and 1 mm, considering that the thickness of the light diffusing layershould be rather increased to broaden the half-value angle.

The fibrous sheet 554 is for enhancing the dimensional stability of thescreen. If the screen is used as a wind-up screen, the fibrous sheet isrequired to prevent the screen pulled down from sagging. Also, when thescreen is unwound in use for projection after storage in a woundcondition, a remaining curling may cause an image projected to bewarped. Therefore, the fibrous sheet 554 is required to have ampleelastic recovery and ample stiffness. Materials to satisfy theserequirements are a woven fabric or an unwoven fabric of glass fibers andplastic sheets of polyester and of cellulose triacetate which areprovided with many small pores.

The plastic sheet for the light absorbing layer 555 is obtained byincorporating a dark, for example, black, dark brown, or dark blue,pigment into the same plastic material as the base material sheet 553,and by forming it. The thickness of the sheet 555 is preferablyequivalent to the total thickness of the base material sheet 553, thereflection layer 552, and the light diffusing layer 551, balancing thescreen in the direction of the thickness.

Also, as shown in FIGS. 26 and 27, the emboss 559 having aconvexo-concave pattern of lenticular lens type on the surface of thelight diffusing layer 551 and light absorbing stripes 530 are disposedat positions other than areas on which light converged by the emboss 559of lenticular lens type is projected (positions corresponding to concaveportions 559a of the emboss 559, because a projection light ordinarilyenters the screen in the normal direction thereto) on the surface of thereflection layer 552 on the side of the light diffusing layer 551. Thereare no light absorbing stripes 530 provided at portions corresponding toconvex portions 559b of the emboss 559. In other words, since theprojection light enters the projection screen nearly in the normaldirection thereto (vertical incidence), the concave portions 559a areregions other than those on which the projection light is converged.

The emboss 559 longitudinally extends in the y direction in FIG. 27, andthe light absorbing stripes 530 also correspondingly extend in ribbonform in the y direction. FIG. 26 is a section indicated by A--A in FIG.27.

The light absorbing stripes 530 can be formed by printing or coatingwith an ink or a coat containing a black pigment, for example, carbonblack. They can also be formed by metal plating, vapor deposition,sputtering, or the like, using a black metal or metal oxide such as ablack chromium deposition.

By providing the light absorbing stripes 530, unnecessary stray lightssuch as light from an electric lamp and outside sun beam can be absorbedby the light absorbing stripes 530, thereby presenting a clearprojection picture plane with a high contrast.

That is, in FIG. 26, a projection light 1₁ enters the light diffusinglayer 551 at a small incident angle θ (in a condition close to normalincidence). The projection light 1₁ is converged thereafter by theemboss 559 of lenticular lens type, and then reaches a positioncorresponding to a convex portion 559b of the emboss 559 of thereflection layer 552. Then, the projection light 1₁ isdiffusion-reflected by the reflection layer 552, and goes out of thelight diffusing layer 551 as a reflection light 1₂ toward the audience.

On the other hand, an unnecessary stray light 1₂ enters the lightdiffusing layer 551 at a large incidence angle φ. The stray light 1₂ isconverged by the emboss 559, and reaches a position corresponding to aconcave portion 559a of the emboss on the reflection layer 552. Since alight absorbing stripe 530 is provided at this position, the stray light1₂ is absorbed by the light absorbing stripe 530 without going outtoward the audience. For this reason, a clear projection image can beobtained.

The position of the light absorbing stripes 530 is not limited to theabove-described position, but may be any portion excluding the portionon which the projection light 1₁ is focused. Accordingly, the stripesmay be designed according to the curvature, the shape, and thereflectivity of the convexo-concave pattern of the emboss 559, anincident angle θ of the projection light 1₁, and the incident angle φ ofthe stray light 1₂.

Another embodiment of the reflection type projection screen will bedescribed with reference to FIG. 28. The reflection type projectionscreen shown in FIG. 28 has backing base materials 553, 554, 555 formedby laminating a light absorbing layer 555, a fibrous sheet 554, and abase material sheet 553 in order. A transparent support sheet 551 ispositioned through a transparent adhesive layer 555 on the backing basematerials 553, 554, 555, and formed on the support sheet 511 is aconvexo-concave pattern lens surface having concave portions 512a andconvex portions 512b by an ionizing radiation curing resin 512. Thelongitudinal direction of the convexo-concave pattern lens surface 512a,512b is along the y direction in FIG. 28.

Also, light absorbing stripes 530 are provided at positionscorresponding to the concave portions 512a of the convexo-concavepattern lens surface on the surface of the support sheet 511 on the sideof the base material sheet 553.

In the reflection type projection screen as shown in FIG. 28, the lightabsorbing layer 555, the fibrous sheet 554, the base material sheet 553,and the light absorbing stripes 530 are the same as those shown in FIGS.26 and 27.

As described above, if the convexo-concave lens surface has a patternother than the lenticular lens, the light absorbing stripes 530 are notnecessarily of stripe form.

The ionizing radiation curing resin 512 used here may be chosen fromknown resins, preferably one having a viscosity below 5000 cps,particularly of 1000 cps. The viscosity of the resin is determined byselection of a suitable monomer, oligomer, or prepolymer.

The ionizing radiation curing resin is a monomer, oligomer, orprepolymer having in its molecule an ethylenically unsaturated bondingor, an epoxy group or a thiol group, specifically, one selected from(meth)acrylates such as an urethane (meth)acrylate and a polyester(meth)acrylate, and unsaturated polyesters. If it is cured by light orultra violet light, a known photo reaction initiator should be added.

The plastic used as the material for the transparent support sheet 511may be any of flexible plastics. The support sheet 511 is required tohave transparency to a visible light. A polyvinyl chloride is a typicalexample of the material. Particularly, a semirigid or soft material ispreferable, in which a plasticizer is added by about 10-60 parts byweight to 100 parts by weight of polyvinyl chloride. In addition, apolypropylene, a polyethylene, a polyethylene terephthalate, and apolycarbonate is preferably used. The thickness of the support sheet 511is preferably between 25 and 200 mm.

To obtain a high reflectivity and a moderate half-value angle, about0.5-10% by weight of lustrous pigment may be added to the support sheet.

6.2 Outline of Production Method

With reference to FIGS. 29 and 30 the production process of thereflection type projection screen (see FIG. 28) having the ionizingradiation curing resin will now be described.

FIG. 29 is a drawing showing a production apparatus of the reflectiontype projection screen and FIG. 30 is a drawing indicating the positionaligning between the front and the back of the projection screen.

As shown in FIG. 29, a support sheet 511 fed from a sheet feed device525 is directed to an ink pan 520 containing a black ink 527 forprinting of light absorbing stripes 530. A gravure printing roll 521 islocated in the ink pan 527, and light absorbing stripes 530 are formedby printing with a black ink on one surface of the support sheet 511between the gravure printing roll 521 and a press roll 522. The lightabsorbing stripes 530 are printed at a predetermined positions on thesupport sheet 511.

Then, the support sheet 511 enters a drier 523, where the lightabsorbing stripes 530 are dried to become solid. The support sheet 511then passes rolls 540, 540 and a compensator roll 524, and reaches apress roll 506, where the other surface of the support sheet 511 isurged against a rotary intaglio 505 by the press roll 506.

The rotary intaglio 505 is provided with recesses 515 of lens form on acylindrical printing material. The recesses 515 may be made by a methodof direct lathe machining on the cylindrical printing material, by amethod of cutting such as milling with a mill formed by theelectroforming process, or by the electroforming process. Materialsusable for the rotary intaglio 505 are metals such as copper, chromium,ion, and the like, synthetic resins such as NBR, epoxy, ebonite, and thelike, and ceramics such as glass. The size of the rotary intaglio 505 isnot specifically limited, and may be suitably determined in accordancewith a size of the screen to be produced. A drive apparatus is providedfor the rotary intaglio 505 to rotate the same in synchronism with thesupport sheet 511, though not shown.

At an outer periphery of the rotary intaglio 505, an ionizing radiationcuring resin liquid 513, for example, an ultra violet light curing resinliquid composed of a formulation mainly containing a prepolymer ofpolyester acrylate and an acrylate monomer is supplied from a T die typenozzle 516. Thereafter, the ionizing radiation curing resin liquid 513is supplied into the concave portions 515 of the rotary intaglio 505.

Ultra-violet light is projected toward the support sheet 511 urgedagainst the outer periphery of the rotary intaglio 505 from an ultraviolet light source (high-pressure mercury-vapor lamp or the like) 508adisposed outside thereof. In this case, the ionizing radiation curingresin liquid 513 is cured to form a convexo-concave pattern lens surfaceof the ionizing radiation curing resin 512 with concave portions 512aand convex portions 512b. Simultaneously, the convexo-concave patternlens plane is bonded to the support sheet 511.

Thereafter, the support sheet 511 and the ionizing radiation curingresin 512 of convexo-concave pattern lens plane are released by alead-on roll 507 from the rotary intaglio 505. Then, a furtherultra-violet light is irradiated by an additional ultra violet lightsource 508b toward the ionizing radiation curing resin 512 on thesupport sheet 511, fully curing the ionizing radiation curing resin 512.Of course, the irradiation by the light source 508b may be omitted, ifthe curing of the cured resin 512 is sufficient only by the ionizingradiation source 508a.

Next, aligning between the light absorbing stripes 530 and the ionizingradiation curing resin 512 constituting the convexo-concave pattern lensplane will be described.

As shown in FIG. 30, upon the printing of the light absorbing stripes530 on the support sheet 511, first register marks 531 aresimultaneously printed (FIG. 30 (A)). Further, upon the formation of theionizing radiation curing resin 512 on the support sheet 511, secondregister marks 532 are simultaneously formed (FIG. 30 (B)).

Then, the first register marks 531 and the second register marks 532 aredetected by paired optical sensors 529, 529 disposed above and below thesheet on the downstream side of the rotary intaglio 505. If there is anoffset between the first register mark 531 and the second register mark532, the compensator roll 524 is moved by a control device 535 so as toincrease or decrease the path length of the support sheet 511, therebycorrecting (registering) the offset between the first and the secondregister marks 531 and 532.

Instead of the paired optical sensors 529, 529, a pair of televisioncameras may be used for detecting the first and the second registermarks 531 and 532.

An offset in a direction of width of the support sheet 511 may becorrected by moving the gravure printing roll 521 and the rotaryintaglio 505 in the direction of width.

Next, on the support sheet 511 having the ionizing radiation curingresin 512 and the light absorbing stripes 530, backing base materials553, 554, 555 comprised of a light absorbing layer 555, a fibrous sheet554, and a base material sheet 553 are laminated through an adhesivelayer 557, producing a reflection type screen (FIG. 28).

Industrial Application

According to the present invention, a reflection type projection screenwhich has a suitable diffusing power and reflectivity and is easilyhandled is readily obtained. Such a reflection type projection screen isused for projection of movies or the like.

We claim:
 1. A reflection type projection screen provided in order witha light absorbing layer (5) of a dark plastic sheet, a fibrous sheet (4)of glass fibers, a base material sheet (3) of a white, opaque, flexibleplastic, and a light diffusing layer (1) of a translucent, flexibleplastic into which a lustrous pigment or calcite powder is incorporated,wherein a convexo-concave emboss (9) is formed on the outer surface ofthe light diffusing layer (1).
 2. A reflection type projection screenaccording to claim 1, wherein an outside frame (10) printed with a darkink is provided on the outer periphery of the outer surface of the lightabsorbing layer (1).
 3. A reflection type projection screen according toclaim 1, wherein a light absorbing portion (11) is provided at aposition corresponding to each concave portion (9a) of the emboss (9) onthe surface of the base material sheet (3) on the side thereof adjoiningthe light diffusing layer (1).
 4. A reflection type projection screenprovided in order with a light absorbing layer (5) of a dark plasticsheet, a fibrous sheet (4) of glass fibers, a base material sheet (3) ofa white, opaque, flexible plastic, a irregular reflection layer (2)printed with an ink containing a lustrous pigment or calcite powder, anda light diffusing layer (1) of a translucent, flexible plastic intowhich a lustrous pigment or calcite powder is incorporated, wherein aconvexo-concave emboss (9) is formed on the outer surface of the lightdiffusing layer (1).
 5. A reflection type projection screen according toclaim 4, wherein an outside frame (10) printed with a dark ink isprovided on the outer periphery of the outer surface of the lightabsorbing layer (1).
 6. A reflection type projection screen according toclaim 5, wherein a light absorbing portion (11) is provided at aposition corresponding to each concave portion (9a) of the emboss (9) onthe surface of the irregular reflection layer (2) on the side thereofadjoining the light diffusing layer (1).
 7. A reflection type projectionscreen provided in order with a light absorbing layer (6) of a solidprint layer of a dark ink, a base material sheet (3) of a white, opaque,flexible plastic, a fibrous sheet (4) of glass fibers, and a lightdiffusing layer (1) of a translucent, flexible plastic into which alustrous pigment or calcite powder is incorporated, wherein aconvexo-concave emboss (9) is formed on the outer surface of the lightdiffusing layer (1).
 8. A reflection type projection screen according toclaim 7, wherein an outside frame (10) printed with a dark ink isprovided on the outer periphery of the outer surface of the lightabsorbing layer (1).
 9. A reflection type projection screen according toclaim 7, wherein a light absorbing portion (11) is provided at aposition corresponding to each concave portion (9a) of the emboss (9) onthe surface of the fibrous sheet (4) on the side thereof adjoining thelight diffusing layer (1).
 10. A reflection type projection screenprovided in order with a light absorbing layer (6) of a solid printlayer of a dark ink, a base material sheet (3) of a white, opaque,flexible plastic, a fibrous sheet (4) of glass fibers, a irregularreflection layer (2) printed with an ink containing a lustrous pigmentor calcite powder, and a light diffusing layer (1) of a translucent,flexible plastic into which a lustrous pigment or calcite powder isincorporated, wherein a convexo-concave emboss (9) is formed on asurface of the light diffusing layer (1).
 11. A reflection typeprojection screen according to claim 10, wherein an outside frame (10)printed with a dark ink is provided on the outer periphery of the outersurface of the light absorbing layer (1).
 12. A reflection typeprojection screen according to claim 10, wherein a light absorbingportion (11) is provided at a position corresponding to each concaveportion (9a) of the emboss (9) on the surface of the irregularreflection layer (2) on the side thereof adjoining the light absorbinglayer (1).
 13. A reflection type projection screen provided in orderwith a base material (103) with both faces being dark and a lightdiffusing layer (101) made with a translucent plastic sheet into which aplatelet-shaped lustrous pigment (102) is incorporated.
 14. A reflectiontype projection screen according to claim 13, wherein the base material(103) comprises a lamination of a backing sheet (104) of a dark plasticsheet, a fibrous sheet (105) of glass fibers, and a middle sheet (106)of a dark plastic sheet.
 15. A reflection type projection screenaccording to claim 13, wherein a convexo-concave emboss (109) isprovided on the outer surface of the light diffusing layer (101).
 16. Areflection type projection screen according to claim 15, wherein a lightabsorbing portion (111) is provided at a position corresponding to eachconcave portion (109a) of the emboss (109) on the surface of the basematerial (103) on the side thereof adjoining the light absorbing layer(101).
 17. A reflection type projection screen comprising a flexiblesheet, wherein a plurality of small openings (208) are provided at leastat a position in the vicinity of a speaker.
 18. A reflection typeprojection screen provided in order with a light absorbing layer (205)of a dark plastic sheet, at least one (204) of a fibrous sheet withflexibility and a base plate with stiffness, a base material sheet (203)of a white, opaque, flexible plastic, a irregular reflection layer (202)printed with an ink containing a lustrous pigment or calcite powder, anda light diffusing layer (201) of a translucent, flexible plasticcontaining a lustrous pigment or calcite powder, wherein aconvexo-concave emboss (209) is provided on the outer surface of thelight diffusing layer (201) and wherein a plurality of small openings(208) are provided at least at a position in the vicinity of a speaker(212) located behind the light absorbing layer (205) through whichopenings sounds from the speaker can pass.
 19. A reflection typeprojection screen according to claim 18, wherein an outside frame (210)printed with a dark ink is provided on the outer periphery of the outersurface of the light absorbing layer (201).
 20. A reflection typeprojection screen according to claim 18, wherein a light absorbingportion (211) is provided at a position corresponding to each concaveportion (209a) of the emboss (209) on the surface of the irregularreflection layer (202) on the side thereof adjoining the light absorbinglayer (201).
 21. A reflection type projection screen provided in orderwith a light absorbing layer (206) of a solid print layer of a dark ink,a base material sheet (203) of a white, opaque, flexible plastic, atleast one (204) of a fibrous sheet with flexibility and a base platewith stiffness, a irregular reflection layer (202) printed with an inkcontaining a lustrous pigment or calcite powder, and a light diffusinglayer (201) of a translucent, flexible plastic containing a lustrouspigment or calcite powder, wherein a convexo-concave emboss (209) isprovided on the outer surface of the light diffusing layer (201) andwherein a plurality of small openings (208) are provided at least at aposition in the vicinity of a speaker (212) located behind the lightabsorbing layer (206) through which openings sounds from the speaker canpass.
 22. A reflection type projection screen according to claim 21,wherein an outside frame (210) printed with a dark ink is provided onthe outer periphery of the ourwe surface of the light absorbing layer(201).
 23. A reflection type projection screen according to claim 21,wherein a light absorbing portion (211) is provided at a positioncorresponding to each concave portion (209a) of the emboss (209) on thesurface of the irregular reflection layer (202) on the side thereofadjoining the light absorbing layer (201).
 24. A reflection typeprojection screen provided in order with a light absorbing layer (305)of a dark plastic sheet, at least one (304) of a fibrous sheet withflexibility and a base plate with stiffness, a base material sheet (303)of a white, opaque, flexible plastic, a irregular reflection layer (302)printed with an ink containing a lustrous pigment or calcite powder, anda light diffusing layer (301) of a translucent, flexible plasticcontaining a lustrous pigment or calcite powder, wherein aconvexo-concave emboss (309) is provided on the outer surface of thelight diffusing layer (301) and wherein the convexo-concave pattern ofthe emboss (309) has either no periodicity or a periodicity with aperiodic direction of the convexo-concave pattern inclined at an angleof 15-75 degrees to a direction of arrangement of projection pixels(316).
 25. A reflection type projection screen according to claim 24,wherein an outside frame (310) printed with a dark ink is provided onthe outer periphery of the outer surface of the light absorbing layer(301).
 26. A reflection type projection screen according to claim 24,wherein a light absorbing portion (311) is provided at a positioncorresponding to each concave portion (309a) of the emboss (309) on thesurface of the reflection layer (302) on the side thereof adjoining thelight absorbing layer (301).
 27. A reflection type projection screenprovide in order with a light absorbing layer (306) of a solid printlayer of a dark ink, a base material sheet (303) of a white, opaque,flexible plastic, at least one (304) of a fibrous sheet with flexibilityand a base plate with stiffness, a irregular reflection layer (302)printed with an ink containing a lustrous pigment or calcite powder, anda light diffusing layer (301) of a translucent, flexible plasticcontaining a lustrous pigment or calcite powder, wherein aconvexo-concave emboss (309) is provided on a surface of the lightdiffusing layer (301) and wherein the convexo-concave pattern of theemboss (309) has either no periodicity or a periodicity with a periodicdirection of the convexo-concave pattern inclined at an angle of 15-75degrees to a direction of arrangement of projection pixels (316).
 28. Areflection type projection screen according to claim 27, wherein anoutside frame (310) printed with a dark ink is provided on the outerperiphery of the outer surface of the light absorbing layer (301).
 29. Areflection type projection screen according to claim 27, wherein a lightabsorbing portion (311) is provided at each position corresponding to aconcave portion (309a) of the emboss (309) on the surface of theirregular reflection layer (302) on the side thereof adjoining the lightabsorbing layer (301).
 30. A process for producing a reflection typescreen, comprising:rotating a rotary intaglio (405) with a surfacehaving a fine convexo-concave pattern in lens form, filling at least arecess portion (415) of the rotary intaglio with an ionizing radiationcuring resin liquid (413), and pressing against the rotary intaglio(405) a support sheet (411) of a transparent, flexible plastic travelingin the rotation direction of the rotary intaglio in synchronismtherewith; rotating the rotary intaglio (405) so as to keep the supportsheet (411) in contact with the rotary intaglio (405), and irradiatingsaid ionizing radiation curing resin liquid (413) with an ionizingradiation to cure the resin liquid (413) and simultaneously to effectadhesion between the cured resin layer (412) thus obtained and thesupport sheet (411), separating the support sheet (411) together withthe cured resin layer (412) from the rotary intaglio (405) to therebymake a lens sheet (401) in which a fine convexo-concave cured resinlayer (412) in lens form is formed on one face of the support sheet(411); and laminating a backing base material (402, 403, 404) with lightdiffusing and reflecting properties on the non-lens face of the lenssheet (401).
 31. A process for producing a reflection type screen,comprising:coating an ionizing radiation curing resin liquid (413) on asupport sheet (411) of a transparent and flexible plastic traveling inthe rotation direction of a rotary intaglio (405) in synchronismtherewith and pressing the support sheet (411) against the rotaryintaglio (405) with a surface having a fine convexo-concave pattern inlens form so as to keep a face of the sheet (411) coated in contact withthe rotary intaglio (405); rotating the rotary intaglio (405) so as tokeep the support sheet (411) in contact with the rotary intaglio (405),and irradiating said ionizing radiation curing resin liquid (413) withan ionizing radiation to cure the resin liquid (413) and simultaneouslyto effect adhesion between the cured resin layer (412) thus obtained andthe support sheet (411); separating the support sheet (411) togetherwith the cured resin layer (412) from the rotary intaglio (405) tothereby make a lens sheet (401) in which a fine convexo-concave curedresin layer (412) in lens form is formed on one face of the supportsheet (411); and laminating a backing base material (402, 403, 404) withlight diffusing and reflecting properties on the non-lens face of thelens sheet (401).
 32. An apparatus for producing a reflection typescreen, comprising: a rotary intaglio (405) with a surface thereofhaving a fine convexo-concave pattern in lens form, a press roll (406)for pressing a support sheet (411) of a plastic against the outercircumference of the rotary intaglio (405), a nozzle (416) for fillingrecesses (415) of the rotary intaglio (405) with an ionizing radiationcuring resin (413), and ionizing radiation irradiating means (408) forirradiating an ionizing radiation toward the support sheet (411) woundaround the outer circumference of the rotary intaglio (405).
 33. Anapparatus for producing a reflection type screen, comprising: a rotaryintaglio (405) with a surface thereof having a fine convexo-concavepattern in lens form, a press roll (406) for pressing a support sheet(411) of a plastic against the outer circumference of the rotaryintaglio (405), coating means (409) for preliminarily coating anionizing radiation curing resin (413) on the face of the support sheet(411) on the side of the rotary intaglio (405), and ionizing radiationirradiating means (408) for irradiating an ionizing radiation toward thesupport sheet (411) wrapped around the outer circumference of the rotaryintaglio (405).
 34. A reflection type projection screen provided inorder with a backing base material (552, 553, 554, 555) of lightdiffusing and reflecting type, and a light diffusing layer (551) made ofa translucent plastic, wherein a convexo-concave emboss (559) isprovided on the surface of the light diffusing layer (551), and whereina light absorbing portion (530) is provided at a position correspondingto each concave portion (559a) of the emboss (559) on the face of thebase material adjoining the light diffusing layer.
 35. A reflection typeprojection screen provided in order with a backing base material (553,554, 555) of light diffusing and reflecting type, a transparent supportsheet (511), and an ionizing radiation curing resin (512), wherein aconvexo-concave lens surface (512a, 512b) is formed on the ionizingradiation curing resin (512), and wherein a light absorbing portion(530) is provided at a position corresponding to each concave portion(512a) of the convexo-concave lens surface on the face of thetransparent support sheet (511) adjoining the base material (553, 554,555).
 36. A process for producing a reflection type screen,comprising:printing a light absorbing portion (530) with a lightabsorbing ink (527) on one face of a support sheet (511) of atransparent, flexible plastic; rotating a rotary intaglio (505) with asurface having a fine convexo-concave pattern in lens form, filling atleast recesses portion (515) of the rotary intaglio with an ionizingradiation curing resin liquid (513), letting the support sheet (511)travel in the rotation direction of the rotary intaglio in synchronismtherewith, and pressing the other face of the support sheet against saidrotary intaglio (505); rotating the rotary intaglio (505) so as to keepthe support sheet (511) in contact with the rotary intaglio (505), andirradiating the ionizing radiation curing resin with an ionizingradiation to cure said curing resin and simultaneously to effectadhesion between the cured resin layer (512) thus obtained and thesupport sheet (511); separating the support sheet (511) together withthe cured resin layer (512) from the rotary intaglio (505), printinglight absorbing stripes (530) on one face of the support sheet (511),and producing a lens sheet (511, 512) provided with the cured resinlayer having a convexo-concave lens surface in which a concave portionis located at a position corresponding to each light absorbing stripe;and laminating a backing base material (553, 554, 555) with lightdiffusing and reflecting properties on the face of the lens sheet (511,512) adjoining the light absorbing portion (530).
 37. A process forproducing a reflection type screen according to claim 36, wherein afirst register mark (531) is formed when the light absorbingportion(530) is printed on the one face of the support sheet (511), asecond register mark (532) is formed when the cured resin layer isformed on the other side of the support sheet (511), and registering ofthe support sheet (511) entering the rotary intaglio (505) is carriedout through the register marks (531, 532).
 38. An apparatus forproducing a reflection type screen, comprising:. a printing device (521,522) for printing a light absorbing portion (530) with a light absorbingink (527) on one face of a support sheet (511) of plastic, a dryer (523)for drying the light absorbing portion (530) printed on the one face ofthe support sheet (511), a rotary intaglio (505) with a surface having afine convexo-concave pattern in lens form, a press roll (506) forpressing the other face of the support sheet (511) against an outercircumference of the rotary intaglio (505) to wrap the support sheetaround the rotary intaglio, a nozzle (516) for filling recess portions(515) of the rotary intaglio (505) with an ionizing radiation curingresin (513), and ionizing radiation irradiating means (508) forirradiating an ionizing radiation toward the support sheet (511) wrappedaround the outer circumference of the rotary intaglio (505).